This is a long drawn out question/theory that's not easy for me to talk about so thanks for taking the time to read this. As a boy I was one of the first to hit puberty. During that time my mother used to buy me extremely tight briefs. I never said anything about it for whatever reason. In order to diminish the pain these tight briefs caused, I would tuck my penis upward (as if there was negative gravity). Because of the constant rubbing, I would get frequent erections that pointed "up". It took my pediatrician to notice the size of my penis (undersized), and convinced my mother to buy me boxers (I was maybe 11ish?). On top of that, when I was 12 or 13, I got circumcised.
Today my penis is very undersized, maybe 2-3 in flaccid and 3-4 in erect, and very thin. And I know for a fact that small penises do NOT run in my family, so it couldn't be genetic. Also my erections still curve up, at about a 150 degree curved angle. Its also very easy for me to get erections, as if there's something physiologically wrong easy.
So here's my theory and let me know what you think. I believe my excessively tight underwear caused severe lack of blood flow to my penis during puberty, resulting in it not growing. I feel like the blood vessels were growing, but because there was a severe lack of space the erectile tissue had no room to grow and just ceased to grow at that point. On a side note, apart from getting very frequent erections, I get "shrinkage" very frequently, even the slightest drop in temperature will cause it to shrink.
And as usual, is there anything I can do now at 20 years old. Thanks for taking the time to read this?