i think the best solution for you would be a support group with people who have similar body issues. Ideally that would be a group for people with small penises but i doubt they have a group just for that. That way you could be around people who are like you and get suggestions on how to feel better about yourself, how they deal with it etc.

I would probably see a male therapist if I were you. They probably would be more likely to be understanding of what you go through because I know a lot of women say size doesn't matter which I believe is true but if you are a guy i am sure it does plus it doesn't help your self esteem much. Maybe some cognitive behavioral therapy might help in getting you to change your thoughts along with some body acceptance therapy I think would help.