Hi there, I'm 19 years old, and lately I can't maintain my erection anymore. When I'm with my girlfriend and trying to have sex I can only maintain about 4-5min erection, and it's depressing. Also I feel like my penis is not as sensitive as it used to be. I used to be masturbate around 3-4 times a week, for about 2 years, and now I only do it maybe 2tkmes a month, I go to bed bed really late usually,