OP, honestly, I thought I could have written this myself.

First, how old is your child? They are much harder to take care of when they are younger but once they get past 5-6 they start to get a bit more self sufficient and things get easier. As you mentioned, they still have "new problems" all of the time. But that means they are growing and you are succeeding as a Dad. Good job :) Someone said to me "The days are long but the years are short" and it's very true. Once they reach age 7-10 they have their own friends and might start to prefer hanging with them. I know it sounds cliche but I miss hearing "Dad do you want to build legos?". Now I have to be the one to ask and I have a 25% success rate :D

I know saying that doesn't make it easier but hopefully learning more about who you are will help you learn who they are too. That to me is why I never stopped wanting to know who I was and why I had such a different experience. All so I could share everything with them and help them build a map for life as they got older. A map I never had.

I was diagnosed as "high functioning autistic" at age 32 and I can relate to a lot of what you're writing but specifically:

>I have approached problems methodically and functionally for as long as I can remember. I am infatuated with problem solving.

Once an interesting problem gets wedged in my brain, I walk through the rest of life spinning on this problem until it is solved or I am bored of it. My brain can even forget to eat and sleep when I'm focused. I learned that this is called "hyperfixating" and autistic people can be prone to it. I'm a dad of two kids and I do my best to be present and available, but as you mentioned, my brain is always tinkering on something in the background. I would try not to beat yourself up about this. What I've learned as my kids got older is that their brain functions the same way as mine. I may be trying to have a conversation and be "present" with them and all they can think about is the problem their brain is stuck on. For my one child, that might be a boss in Minecraft. I'll ask them "How was your school day?" and sometimes it will go ignored and they will respond with a minecraft related statement. That's ok :) I totally understand them now and don't take it personally that their brain is focused on something else.

>I find maintaining social interactions and simple friendships not easy and rather exhausting.

The last time I saw one of my friends was in April of 2022. I had a great time with him but I felt burned out after he left and had a hard time accepting invitations to do things for months after. It's not that I don't have a good time, it's that there's so much input and so many things for me to process that it takes me so long to bounce back. I have friends but I suffer from so much social anxiety that checking my texts or DM's on different platforms can overcome me and pause me in place before I get to respond. Then I'd suffer from the ensuing guilt of feeling like a bad friend for not behaving the "way I'm supposed to". When I have someone in the house who is not my immediate family(wife or kids) I am counting the minutes until they leave. It has nothing to do with them but everything to do with the fact that they are altering my routines and pushing things out of place later in the day.

I wish I didn't feel this way but it's been constant my whole life. I've always been extremely rigid in my schedule and it can cause great anxiety when people drop by unexpectedly and pull me away from something I was planning on doing. Anything that "interrupts" my plans can be emotionally hard to reason with. I eventually get over it but internally it feels so intense that it causes me to go nonverbal. Turns out this is another thing that folks on the spectrum can suffer from.

>Approaching strangers is extremely difficult for me.

I relate to this as well. There too many possible pathways to think through and I'm always caught off guard by some situation or thing that's never been said or happened so my "library" returns a cache miss and my brain can go haywire. I don't know how to "properly" react and I leave "socially awkward" impressions on people. Because of having this experience most of my life, I have preferred to do activities in solitude and I'm happier for it. One thing I learned in therapy that was helpful was "Your wife was a stranger once. How did you overcome that?" So that has helped me think that there are good experiences with strangers still out there. But the social anxiety is still there and overrides any chance that I will want to interact with people. As you mentioned, I'd rather be left alone with the problems I'm thinking about or the activities I want to enjoy.

>I have a library of behavior patterns in my head and try to deduce something from them.

This is a common experience I've read about from other autistic people. It's also exactly how I experience life. I get great anxiety from situations where I don't know how to act or from what to expect from a situation. One time I was asked to "Be in a wedding" and I had no idea what that meant. I thought that was the same as "Would you like to come to my wedding?". It was my best friend so I said yes, but I was very wrong. I had no idea what to expect and it was a nightmare experience for me. I had to spend money on uncomfortable clothing, wear them all day, participate in ritualistic behavior that I had never been exposed to before (and felt bad because they were like, don't you know this??). I had no idea about cuff links, suits, gifts to the bride and groom, doing all these weird dances and like parading out in front of all of their family. Speeches? omg, I wanted to die.

It was an experience I never want to live again. But I love my friend and he's like my brother. How can I feel this way? It really was an eye opening experience for me and I beat myself up for "not getting it" and not enjoying i. But it turns out, I was autistic and this was a new situation for me. New situations can cause a lot of anxiety for autistic people especially without proper expectations established before hand. So I try to give myself a bit of grace when thinking of that memory.

>I still don't like to go shopping, but I do it because I have learned to position myself differently with my thoughts.
Shopping is an awful experience and I am extremely overstimulated any time I step into a retail establishment. Especially any "big box" store. I find them to be an assault on the senses and I truly feel that they are designed to "trap you" and prey on your humanity to get you to spend money. Like true psychological torture to me. Feels like every step I take its some behavioral psychologists little test to see if I'll bite. The digital realm is also like this nowadays but I especially hate when it's in person. One example is the stores that specifically only let you go in "one way" and you have to leave through a maze of specifically placed products to entice you into buying them. I really hate how the experience is crafted to try and trick you in so many little ways and generally gives me more anxiety.

Anyway, what I'm really trying to say here is that I can relate to your experience and I think you should keep on searching for answers that work for you. I'm not saying you're autistic but we share a lot of the same experiences and all I really hope is that you find what you're looking for and that you find peace with who you are. We're all different and even if someone "lands on the spectrum" their experience may be totally different from someone elses. Certainly don't let me speak for all autistic people. But what you're saying lines up with a lot of what I've experienced and what I've read other autistic people experiencing. reddit.com/r/autism has been an amazing resource for me. Find a psychologist who specializes in adult autism and see what it would take to get tested. Not just talking to a therapist but going through the testing process with a psychologist.

Today was the first day in my entire life that I told someone (during a job interview no less) that I was autistic and received an enthusiastic, supportive response. They smiled and said "Me too. We have great support for that here. This company asked me how they could make their offices more friendly to autistic people and implemented my feedback within months of being here because they valued my presence and wanted to make sure I felt comfortable." I was blown away. Every other time I've mentioned it I've received cold responses such as "Ok" and "Oh". I can't blame them, maybe their behavior library returned a "cache miss" too :) Be well.