Hi, Zora. I'm Brandy.
For your question about what it means for your identity....well. Really, nobody and nothing can make you anything than what you are. If you feel Queer - you're Queer.
That's certainly not the end of the story, though. It's a conversation that the two of you are going to have to have at some point, I'd think...regarding YOU and your identity. You do not have to transition (for lack of a better word) just because he is - and he needs to respect you and who you are.
And then there's the T. I certainly haven't dated every transguy on the planet (thank goodness, cuz that sounds wicked time consuming) so I'm no expert. But IN MY EXPERIENCE (which comes with the disclaimer that it's not true for every person every time) sometimes guys can get real self-centred when physical changes start happening. And rightfully so - I get that it's exciting. But for myself...I can only have so many conversations about "is this a new hair?" before I go completely batshit crazy and bolt.
I guess the key to navigating that stage will be lots of talk and boundary setting BEFORE it happens - which I never had the foresight to do. If you can be clear about what you need and your guy can remember that there are two of you in the relationship, you should be good to go.