I'm a 16 year old male. I only lost my V-card about a week ago to my current girlfriend. I couldn't get hard that time but figured it was first time jitters. A couple days later we went at it again. I managed to get hard enough to get going and after 15 minutes she had come twice and I was getting nowhere. I should mention that we were having sex in the shower that time but I'm not sure that makes a difference. Today we had sex again and I could barely keep my dick up. We went at it for 45 minutes. It's odd because when I masturbate to porn or whatnot, I get super hard instantly and last only about 3 minutes. Any advice or information would be helpful.