If you feel you have to monitor your lover, then it won't come out too well. Each party has to give 60 percent. Each party has to vow that they will let the other person know how they are feeling. They have to commit to trying to work the relationship out instead if leaving. There needs to be fun as well.
Size matters only if it matters to the person.
The vast majority of women don't care much about male size when they are in the normal range. It's not so much the size of the boat as the motion of the ocean. Turn ons can be physical or psychological. Your biggest sex organ is between your ears and not between your legs. A big turn on is when a person knows that someone cares about them and is thinking about them.