i feel really bad right now. my girlfriend and i are never EVER able to be alone for some reason (we're both 17) and last night we finally were. i'm a virgin, she's not and we got to a secluded place where we wanted to have sex. we got in the extremely cramped back seat and started going along. i had an erection and i put the condom on but as she started to try and "put me in" i was losing the erection. uhhhhh what the hell is that all about. there's nothing wrong with me physically, i'm on no medication and have had no medical problems whatsoever. i'm really scared about this. i don't know what's going on. help me please.