Well, admittedly, I was at one point probably more bi than anything else. I didn't mind men, though I think I preferred women. However, as I began to develop myself, and choose what I wanted to be, I explored the possibility of men more than I had before. I was only sixteen, so I imagine my sexuality was still quite malleable - and is presently, to a point. I became very split between the two.
However, now at eighteen and six months on HRT, I fully consider myself straight. My interest in women is insignificant... I could not have an intense relationship with another woman, for both the romantic and sexual reasons. I just can't do that.
Additionally, though, I'm really a little asexual as sex is not very fun at all at my present pre-op stage. I just can't stand having that thing still around - I pretend like it doesn't exist, and I don't like it one bit that it has to come to play.
So, I'm asexual with a chance of heterosexuality, pending my SRS. My boyfriend doesn't mind; he's more straight than bi anyway. I'm sure being pre-op is not helping things for him either. However, being the person he is, he's too sweet to say he minds...
I answered "straight" as I doubt I will remain abstinent post-SRS.