I doubt anyone has ever done any actual studies but I would be willing to make a guess there are far more transgender people than there are people with chromosome issues
As to where to go, again to follow the mental illness thread, most people will not be comfortable with a "crazy" person being alone in a washroom with them
And trust me a pre-op trans looks pretty crazy to most normal people
As to OP yes the debate on sexual identity has NOTHING to do with the debate as to whether non-standard are normal or not
I'm sure the Mom in this story was as uncomfortable as anyone can imagine when the drunk — an ordinary factory-issue genetic and mental male as far as anyone knows — forced himself into the Women's Washroom in desperation, and started peeing in her daughter's stall. Like 'drunk', 'crazy' has no connection to trans, gender, sex or washrooms.
Please don't be offended, but I don't trust you as any sort of expert on what pre-op trans look like, not until you tell us why we should. My sweetie's had to explain more than once in washrooms, how born-women adjust their pantyhose, and she doesn't think they're crazy, just unpracticed. My own experience, from work and social interaction has been in single digits, but the guys in dresses haven't been crazy-looking, nor have the butch girls in men's pants. They dress differently, and maybe aren't what I call conventionally attractive. But I'm not gonna be first to throw that stone.
And if the polite skirt-wearing carpenter doing the house down the way thinks I should know which direction that transition's headed, then I'm sure I'll be told. Until then, it's no business of mine. "Good morning" is unisex.