Am I gay or straight?

I remember when I was little I had TV in my room and at the late evening I was switching between channels to "accidentally" get to the dirty channels that showed naked girls. I remember being turned on by those girls. But when I was about 12 I started catching myself on looking for pictures of men and until now, when I am 17 I get turned on only with gay stuff and identify myself as a gay. I just read about the things that during puberty people are starting to get interested in the same sex. But is it that long and that strong(I mean from straight to gay)?I still have cruches on girls, but very rarely and I think I identify myself as a biromantic