I haven't started HRT yet, but my experience so far is that my first priority is to be honorable to the current relationship, and i still enjoy sexual contact with her - but i'm not sure what will happen with that when i start HRT and lose function.
that said, right now when I look at someone and think "they are sexy" it's almost always a female. Though I certainly can distinguish a good looking man when I see one. however, when i think of myself having sex in the future, I pretty much always imagine myself be "taken" by a man.
I've had three oral encounters with a man and thoroughly enjoyed each.
So i would describe myself now as bi, but i would have NEVER considered sex with a man AS a man - it's only as Laura that that was possible.
this isn't to say that there was some sort of homophobia going on - over the years I thoroughly examined the potential that I was gay as opposed to trans and was entirely open to it but i always concluded I'd rather be an ugly celibate woman as a hot gay Lothario.
since I went full time, I did have one very attractive young mexican guy ask me if I was married and i got such a rush from that that i didn't even no how to process it....I've never felt anything like it.
So anyway - I said all that to say this - I HOPE, fervently, that I'm one of those who's attraction does change. I don't have anything against being a lesbian, I love the company of women, but there is something that is just fascinating about finding my interest in guys expanding beyond the ...uh...physical activities.
My first choice is still to be happily bi - but I hope it's Bi on every level and not just about the sex.