Reading your comment breaks my heart. Sorry, it's going to be a long post, and my english skills are questionable...

I'm 35. French. My family used to see the same allergist since I was a kid. One day, after a really bad nose/eyes allergy attack, he told me it was probably psychological. Well yeah, it's kind of psychological when you are losing your mind with your eyes and nose being painful + the headaches. I'm a peaceful guy but the "psychological" BS with his arrogant attitude was too much for me, I was literally about to grab him... I just left without even paying him.
This idiot had the reputation to be the city best allergist, good thing he retired some time later. I was something like 23 or 24. Most internists I saw between 21/25yo didn't really cared about my condition. I guess it was too difficult to find out what was going on with my chronic colds/allergies, my obesity, my permanent tiredness, depression...
Most psychiatrists I had between 21/25yo were absolute trash, the last one tried to calm me with cyamemazine, a strong antipsychotic. Probably the worst time of my life, imagine all the symptoms I listed before + the sedative effects of the cyamemazine... It's like you don't even feel alive anymore.

I hit rock bottom when I was 25. I had severe allergies without even going outside, always tired, 1 or 2 naps every day, suicidal thoughts... I couldn't work anymore to survive.
Well, good thing it happened when I was 25, because in France you can't have any benefit welfare before 25 (except housing welfare). Before 25, sometimes I used to survive with like 200 euros per month, so the 500 euros "social solidarity benefit" was a lot of money to me.
I was a mess since I was a teenager, but for the first time of my life I met someone from the social services who took care of me. She was used to this kind of situation and recommended me a good internist.
I had to "wait" to be 25 until a good internist sent me to a competent pulmonologist who diagnosed with sleep apnea. This is why I was always tired...
My internist also sent me to a good allergist. I finally got skin tested (the family allergist never tested me...). I knew about pollen allergies, not for dust and mites... This is why I was sick all the time without even going outside. Some asthma too.
Things were getting better after trying a lot of psychiatrist, but not great. The years go by...

2021. After seeing a good psychiatrist in a mental health clinic for the last two years. Things got better, she found the best pills "recipe". :o) But most important, she started to "understand" me. She knew something was wrong despite the fact I was feeling happier.
She knew about my chaotic school years, my lack of concentration and focus, and I guess it became obvious when I failed 2 professional training courses this year.

See where this is going ? ... Early november, she sent me to one of her colleague, a specialized psychiatrist. It was brutal, after studying my records and talking to me for 2 hour, he told me he highly suspected a ADHD (attention deficit hyperactivity disorder) and possibly an ASD (autism spectrum disorder). When we were walking to the reception, he told me he was "betting" I was probably around 120/130 IQ, smiling. I was like... Yeah, RIGHT... WTH is he talking about. :/
ADHD was plausible to me but I was skeptical about the rest Reading articles about autism or Asperger sometimes felt very familiar to me, but that's about it.
The IQ thing ? Dude, I always felt stupid as long as I can remember. School was terrible. Rates, people, family, everything was terrible. Same as an adult, I always felt too "mental" to do anything "basic" but to dumb to do anything "better". My only good years were as a security guard on a large industrial site. Lots of night shifts, alone...

Next steps : 3 appointments with a psychologist. A first meeting, the WAIS test the next week, and the results another week later. It was among the three longest weeks of my life. Waiting for the results was a nightmare.
It's late november, ADHD is confirmed, heterogeneous IQ between 100 and 130... As far as I understood, I have good cognitive capacities, especially with visual stuff, but everything related to memory is terrible... It's such a mess I don't have a homogeneous IQ.
It was weird to feel "smart" with the cubes and other visual test. At school, maths were my nemesis, but I remember having fun with geometry.
They're still some doubts about an ASD. I was kind of shocked during the last appointment, it was a lot of information to handle. But it seems it's harder to get diagnosed when you're an adult. The psychologist needed to talk to my parents, my school grades, some specific medical informations about my childhood, etc. My mom is gone, I don't want to see my dad anymore and I have nothing about my childhood.
If I want to find out about a possible ASD, she told me we could try a "social cognitive exploration" one day. I'll wait until I feel less lost...

Early december. I'm finishing my 6 months failed professional training courses and the ADHD/ASD specialized psychiatrist put me on methylphenidate right away. "Concerta LP 54mg". "It's going to boost you up. Side effects are going to help you losing some weigh, pretty cool uh ? It's similar to amphetamines." Wait WHAT ?
This is insane. I mean, nothing's going to change about human interactions etc, but it feels like my brain can finally do things without quickly ending exhausted. It's not perfect, but I don't feel this heavy "mental fog" anymore when I try to do something mentally demanding...

This year was an emotional roller coaster. The 6 month courses probably were one of the worst experience of my life, content was boring, terrible teachers, toxic students, I ended up mentally broken... And then all of this happened.
It's a bittersweet feeling. I can't put the last 6 months behind me, I can't forget how all this toxicity affected me. I feel really great thanks to the methylphenidate. Learning seems possible, I can finally enjoy things like playing online with my friends without feeling mentally exhausted after 1 or 2 hours. But sometimes I just lose it, thinking about how things could have been different with good parenting and earlier medical care.

How to you start your life at 35yo ? I'm not even sure I'm going to live another 35 years.

Sometimes I have flashbacks of my previous life, like in high schoool, some really nice memories like being sent to the school psychologist because they suspected me of drug use because I was tired and alone all the time. I think I never touched anything until my first beer around 21yo. Yeah, 21, this is how lame I was, but to my school I was probably a drug dealer. Good job french educational system !
Domestic violence, sexual abuse. My interactions with teachers/school psychologists/family MD/police/child protection services/etc were an endless failure.
All my life I have been teased and bullied for being weird and lazy. At school, at home, in family meetings, at work...

I don't even know if I really tried to hide things, I was just used to think everything weird or terrible in my life was just normal.
How the hell are you supposed to understand something's wrong when you have no idea of what's good or wrong.
You can't place yourself on a scale if you don't know what 0 or 10 means.
So yeah, you spend years hearing people calling you lazy, unmotivated. The "where there's a will there's a way" people, the "you're just making excuses" people.
Same story, I turned down everything, which can sometimes cause bad reactions from your "friends", which can make you feel even worse...
This is why your post overwhelmed me. I felt this for decades.

I've been doing a big cleaning up of my entourage for the last 2 years so I'm not going to have a lot of decisions to make about ADHD and a possible ASD.
I'm just curious about how I'm going to use different learning methods so I can move forward.
I don't know about human interactions... I don't think I can't say anything positive about this, there's too much hate in me.
There is one thing for sure, you can't fix toxic people.

Take care.