Hi! My youngest is a trans guy, so at this point I am an older parent (mid 50s). They had to literally come out to me because my idea of acceptable womanhood is so wide the fact that they dressed like a 40 year old butch lesbian in high school did not make me think anything, nor the binder, both the youngest 2 do that and both prefer girls, so I just figured both were gay. It is funny he just figured I'd be happy, since I only spawned girls, to have one be a boy. You are right that kids are lasseiz-faire about it.
I did have definite anxiety around this, much more than the kids do, they just find it normal to choose. The state took away underage people's choice on hormones so there was enough time for me to feel more settled, and we talked a lot about the medical side. He is lucky in build, I am tall for a lady, with gentle not dramatic curves, a more androgynous build and he got that (my tallest kid! Only one taller than me!) so could pass before doing any hormones, it was less urgent than it might have been if he read more girly in body type.
Now he is 19, which puts it even more firmly in the territory of not my business.
You are most welcome to message me if you want to.