I can't say I'm the best person to give advice, but I definitely understand where you're coming from about getting angry around girls. I've even responded, "What the hell do want from me?" when she just wanted to dance. Also being nervous about what she's thinking, that I'm not good enough for her, that all the other guys around are better and more manly then me and I'm just an insecure psychotic looser. I've felt that way for a long time, so it's kind of ingrained into my head. I think part of it is a dominance thing. Sometimes I think I need to just let it go, approach a girl and talk to her like any other person.

I think these feelings are within the realm of normal, so I wouldn't get too worked up about it. Considering you're mood fluctuation is purely situational (it only happens around women you'd consider getting with), I agree that it's probably not bipolar. Keep in mind also that meds can kill you're sex drive, which may defeat the purpose in your case.

Oh, and I've also been watching porn since I was 12.