Please try not to be so hard on yoursef. Maybe it's the whole casual sex thing with girls. Maybe what you're really looking for is a real connection with a woman. when I was you age I had the same thoughts about women (I am female). I even went as far as to try and have an encounter with another woman. Needless to say it didn't work out because when it got down to business I freaked. Now, I'm not telling you to go and have sex with a man, that was just my experience.
When I finally fell in love that's when sex with a man got good again. Having friends with benefits gets a little old sometimes.
Also, I think there is nothing wrong with looking at and liking teh anatomy of the same sex or even having a fantasy about them. I happen to think that women's bodies are so much more beautiful than a man's. And by the way, the majority of women that I know feel the same.
I don't know if I've helped you in any way, just know that I feel for you situation. Take care of yourself.