It's normal. If you really were okay with being gay you wouldn't be considering transitioning. Overreacting to someone saying you're gay and denying it like there's no tomorrow, now that might be homophobia in a way. But just not liking to be called gay, that's all right. It implies that you're a man, and if you feel like a woman, it's something you're ultimately not, probably. And being called something you're not just doesn't feel good.
However, right now you're into men and until you transition you're a man. Which technically makes you a gay man. So while it's okay not to like it, get used to it, because for now and for an undetermined period of time, it is true.
Besides, studies are starting to show that probably, androphilic (into men) transsexuals come from the same source as gay men, that basically a gay man might be someone with a slightly feminized brain, and that an androphilic transsexual has a more extensively feminized brain, which would in the end make androphilic trans women "so gay they're women".
So if those findings are confirmed, in the end, all of us straight trans women are technically speaking a kind of gay man, haha. I don't find it exactly thrilling to imagine either, but if it's what it is, then that's that. And well, to be honest, I do recognize myself a little in some gay men, even though I know I'm not quite the same.
(Don't worry about your rights and whatnot, though. Those were never based on some recognition that we are "true women inside" but on the simple fact that the only effective means of treatment is for us to transition, live and be recognized as female, which doesn't change.)