Can I throw a wrench into some theories?
I'm not sure my sexuality so much "changed" as it opened up the moment I began to explore transition. The moment I realized I really was going to be going down this road of transition. Before I'd even had my first gender therapy session and months before I even began HRT.
Assuming our brains are hardwired to our true gender from birth and some just may not recognize it for whatever reason until later in life, I'm guessing when I thought I was "honestly" asking myself constantly if I was "gay" as a boy and man and always coming up with "no" as an answer, I was not able to access some part of my psyche, whether it was social pressure or conditioning, I'm not sure. I think that once I realized I would be living in the world as a woman my brain somehow allowed itself to open my thinking to my true nature in that, yes, I loved girls and then women, but guess what! I also have this inner desire to be with a guy! To love and be loved by a guy! To...um...be
intimate with a guy!
It gets weirder...I thought I would have had GRS long, long ago. It didn't happen that way. I've been stuck with this dangly bit for far too long and GRS seemed too far out of reach for me. While I did end up marrying a man, I'm so uncomfortable with my bit, even post-orchie, that I have no desire to have it even seen, much less utilized, so we've had a sexless marriage. It's caused major issues for both of us to the point that we're in a holding pattern until we just sign the paperwork to finalize our divorce.
I started thinking that I wanted to be with a woman again. I want to experience physical and emotional intimacy with a woman for the first time in I-don't-know-how-long.
I was suddenly given huge good news a couple of months ago and was able to begin exploring the possibility of having GRS, finally! But my searching and searching was not encouraging. Prices have gone up considerably since I first looked into this 16 years ago so it began to feel just as out of reach as it had for the last decade or more. A couple of days ago I found out that two local clinics took my insurance when previously they didn't! Woah! This might actually happen! HF!
Now, with the very real possibility that I might finally have a place to put a guy's bits and get enjoyment out of it, I'm kinda changing my mind again! To finally experience proper sex with a guy is starting to awaken my long-dormant libido. There are stirrings down there, but they radiate to my entire being!
I'm even thinking that there might be a possibility my marriage might be saved, but realistically, I'm pretty sure it's too far gone to be resuscitated.

So...where the hell am I going to find a guy that finds tomboys that like to use machinery and work in CG attractive?
I'm weird.