Another bit of advice would be to let your daughter decide since I believe this is her choice and to steer her toward what you would prefer due to transition etc. would be wrong. Like I said, Brianna is a good compromise, particularly since being "dadded" can cause distress whilst out in public. What you need to weigh up, I think, is that if you are economical with the truth with regards to your transition, she may end up resenting or even rejecting you in the future. You are already raising your daughter by yourself, which I think is awesome, and the bond you will have built up could be severely damaged.
Maybe you could ask her when she is older and able to understand things a bit better, what she would prefer to call you. The other aspect of this is whether
she might find it uncomfortable to call someone who is a woman "dad", particularly in front of her school friends.
From my point of view, I let my son drive this area of my transition so far. He calls me either dad or Nikki. I think it's up to me to live with the consequences of being "dadded" as I was the one that needed to transition. I still get a fathers day card and a box of chocolates, so as long as the chocolates keep coming, I can live with this.

This is, of course, only my point of view.
I really hope it all works out well for the both of you.
Nikki