I've had male bonding fantasies ever since I was small, and they began to be sexual when I was about thirteen. Men on men seemed perfectly natural and right to me. I didn't understand what any man could see in a girl. So I thought I was the freakiest pervert on the planet and, for a long time, didn't understand that most gay men have similar childhood fantasies. (Of course, I didn't know for sure that gay people existed until I was eighteen. I was born in the early sixties, so things were different for me.)
Bottom line (haha), I have identified as a gay man for most of my adult life, once I discovered a few things (such as the gay part of town and the very existence of FTMs). I live as a gay man now and am accepted by the gay community, although my friends do not know about my past.
Some gay trans men wind up with bi cisgender men, some with gay cisgender men, and some with other trans men. A few pair up with men who identify as straight but "make exceptions." If you are exclusively gay, that does limit your options, but that doesn't mean game over.
I'll tell you something, though. I don't know if I'll ever be in a relationship again. But the more comfortable I become with myself, the less I worry about it. So I still think about it, but not as much as I used to. If you focus on getting right with yourself, you might worry less about partners.