I don't know why I couldn't take low dose anymore, but I ended up seriously depressed by the end of it. I'm not sure when the depression started as I didn't realize until it got really bad. I must have gotten used to it at some point, or perhaps I was trying to ignore it.
I didn't really understood what dysphoria was before that, but when everything got bad that did too. And then I realized I'd had it when I was around 18 and tried cross dressing. I thought that appalling feeling was just that cross dressing wasn't my thing. If only I'd known. What an idiot.
That was a really scary time, and I could see it was going to end badly if I didn't do something. I finally saw a doctor and started a transitioning dose, saw a psych, made a few decisions, and all the depression just evaporated.
If it happens again I'll end up socially transitioning, because I can't face that again.