Oh yeah, female puberty? That was
horrendous. I felt bad when I was younger, but puberty was the start of a lifelong hatred of my own body. I would've been much happier if I could've taken hormone blockers to limit the damage.
I think the reason why we're seeing more young trans people is because there's more information available today. When I first realised I was trans (back in 1990) there was certainly no information about FtMs: I had to search very hard to find out anything at all and I didn't like what I saw. So I figured I couldn't do anything about it and I'd best carry on trying to figure out what it means to be 'female', hence why I'm transitioning in my 40s.
Today you can browse the Internet from the privacy of your bedroom, so younger people coming up behind us are able to accept who they are at a much earlier age. But you raise the interesting point about there being fewer visible young MtFs and I think I may have an answer for you.
I recently read a very interesting paper (
http://www.gjss.org/images/stories/volumes/7/2/3.%20Kennedy%20and%20Hellen.pdf) about the experiences of transgender children. In it, they reported that only 2% of MtF children are allowed to express their correct gender identity in school, rising to a mere 4% who were allowed to express their gender identity at home. As opposed to FtM children, of whom up to 18% were allowed some form of gender identity expression at school, and 45% were allowed to express their identity at home.
This probably makes it easier for FtMs (in general) to come to terms with our gender identity at a younger age than MtFs (in general). The few examples of very young MtFs we've recently seen in the media all seem to fall into that low percentage who had supportive parents and schools and were therefore permitted some visible expression of their gender identity.
I then read somewhere (I think in a different document by the same author) that this may be due to the different ways in which boys and girls are socialised. Boys are socialised - by their parents and by other boys - with a rigid system of paranoia against the 'other'. They defined the 'other' as anything that was not typically masculine, and anything feminine was particularly shunned as being weak or unacceptable. So male-born children are under extreme pressure to not display any feminine characteristics. The author (who is MtF) suggested that FtM children might have an easier experience of childhood because we don't suffer the same conditioning, but I disagree: this male allergy to 'femaleness' was the reason why my male friends shunned me when they got to a certain age. They couldn't handle their friends constantly asking "why are you hanging out with that
girl?". And to be honest, I sure as hell didn't want to hang out with girls either, so that left me quite lonely.
They also said that this pressure on MtF children is so extreme that many grow up to attempt 'extremely masculine' activities, such as joining the military, in an attempt to prove themselves as meeting societal expectations of maleness, both to themselves and to society in general.
Bottom line is: MtFs apparently have far fewer opportunities to express their gender identity whilst growing up, so it may well take them longer to accept themselves and do what needs to be done. And this problem would have been worse for MtFs born before, say, the 1990s, back in the days when society was even more rigidly sexist and male-oriented than it is today.