Does this neccassarily mean I'm a lesbian?

I was watching a reality tv show, which is about new couples and I just kept noticing how gorgeous the girls are and such. But the thing is, I can't picture doing sexual things to girls. Does this make me a lesbian? And lately I haven't been attracted to guys or for that matter anyone, i feel so empty inside. I used to get turned on just thinking about sex, but not anymore :/ Am I a lesbian?