Is it normal for a girl to only watch gay porn?

I'm a girl and I have been watching porn since I was about 14 and for so reason I am only interested in gay (guy on guy) porn. It started like any other young teeneager being curius about the opposite sex. At first I tried to watch normal porn but seeing other naked women just grosses me out. So i searched for gay porn and it turns me on so much. I used to watch it every single day when i came home from school. Did i hurt myself by watching this at such a young age and now to the point where its the only thing im attracted to? Is this bad? Has this happened to anyone else? I have a bf and I ask him would he ever do anything with another guy and he says no and it disappoints me greatly =(. He tries to do things to turn me on on webcam but i rarely get wet. I have trouble getting aroused without using gay porn.