I think another reason we are "under-reported" is that we're just not taken seriously. And that situation existed even before we come out. No matter how great the U.S. claims to be, or is believed to be, no matter how it preaches equality for all, females still are not as important.* Too many trans boys are considered nothing but tomboys.
Think about it... if a boy says he wants to be a girl, everyone (including women) will bend over backwards and jump thru their skin and several hoops and loops to convince him he doesn't want to be a girl. They will do all they can to convince him of that.
If a girl says she wants to be a boy, she's either told she's just being silly, or she's ignored, or she's patronized, or she's told all little girls want to be boys until they [reach a certain age], or boys are nasty. It's just not taken seriously. AND... when have you ever seen a trans boy/man post about his parents having tried to "beat the boy out" of him? Seems it's only trans girls that experience beatings at the hands of unapproving, unaccepting, homo-/transphobic parents.
Quite often, females are raised learning that anything they have to say is insignificant, of little importance. Their voice carries no weight. Some, after a while, learn to just say nothing.
*I read an article several years ago that indicated, even is the U.S., there are many more couples who decide not to have more children if their first born is male, as compared to couples who's first born is female. In more cases than not, if the first born is female, an attempt will be made to produce a son.