Hello Rachael_S: Well, as far as the idea of a letter goes... sure send a letter. What harm can it do? She may or may not read it. It sounds as though the relationship is in the past, though, & I would suggest that you not pursue it beyond sending the letter, unless she responds positively. If she does not respond, then just let it go. Sometimes when a thing is over, it's just over & there's nothing one can do but move on. Should your ex respond negatively, I would recommend not responding. Just drop it at that point. There's no purpose served by rekindling a flame war, if you know what I mean.

As far as your concerns with regard to who you are & aren't attracted to: you mentioned that you'll be graduating soon. I presume you'll be needing / wanting to find employment. It seems to me that, at this point, you might want to be focusing on starting to look for employment opportunities (assuming you don't already have something lined up) & make your decision with regard to where you're going to live based on where you're going to be working.

As far as the question of attraction to women, trans women, & trans men goes, you know, what the LGBTQ community is trying to move toward is a society where each person is just themselves. We're not trans, or bi, or any other label. So my thought would be don't worry about if a particular person is gay or bi, or trans, or whatever, just focus on each person you get to know as an individual & see how the two of you "click". At some point, the right person will come along. And at that point what difference does it make? This kind of openness is to be celebrated. And you are to be celebrated for your openness!