I m 18 and a few months ago I had surgery where the foreskin on my penis was cut and widened, it was a success in the regard the foreskin can now retract, a few weeks later I began oral sex with my girl friend and that was fine, but when I tried to have sex I can never get it hard enough to penetrate vagina, my girlfriend is fine with the whole thing, but I m justt worries , any ideas of what might be wrong? Thanks