Hi Julie Marie, I'm not as experienced as you since I'm only 1,5 years into full transition but I do feel that same pendulum effect.
Before I came out I was a skirted men, trying as hard as I can to live my gender dysphoria without coming out as trans.
Since coming out, I just bursted with pink everything and girly stuff. Wearing skirts, tights, summer, winter, wind, rain, snow, whatever.
Now I'm becoming more and more boyish with an "in between" look with jeans and hoody where I feel feminine and confortable. I still have a slight beard shadow so fondation is still a must but I can't wait to go out make-up less.
I personaly explain it by saying that at first I fought hard to pass. As time is going by and passing easier, I'm feeling I'm a girl instead of wanting to look like a girl.