This is a really interesting discussion by the way - thanks to everyone explaining the issues! It's something I've not really thought about in detail before.
I'm like forfucksake in that I end up very conflicted when working through things! Part of me is all in favour of making things that bit easier for vulnerable groups and minorities, but then, as others have said - where do you draw the line? We can't say "twaw when it comes to some types of changing rooms and toilets but not for sport or prisons or xxxx". And why is it another vulnerable group (women) that has to give up their space to accommodate it? (I assume the same goes for men accommodating transmen, but that never seems to be considered - presumably as transmen are the only minority in that situation, so doubly vulnerable). Yes, a "third space" could be created, but that still ends up with the "othering" issue.
Im sure there's more to it (probably me being simplistic because I'm not really believing in gender again!) but I don't know why we don't put more emphasis on broadening what is "acceptable" for men and women. If TW "feel like they are a woman" - what aspect of that feeling can't be met by being male? It's obviously not going to be "I feel like I need to go into a woman's toilet" or "I want people to refer to me as a woman" (those are effects, rather than causes) or even "I feel like I need to have lower pay and less responsibility because I might go off and get pregnant"... But if it's "I fancy men", why not identify as a gay male? If it's "I like posh hair and heels and dresses" (
because what woman doesn't? Not a sexist assumption at all... ) why not wear those things as a man... and lobby for that to become more socially acceptable rather than lobbying to be allowed "to be a woman" in order to be allowed to wear them. If you want more delicate features, have surgery to have more delicate features as a man, and accept that you may be given a mixture of pronouns as a result. If you are wrongly pronouned, you can correct people without it being a huge insult, or not bother if you don't care.
DS is often assumed to be a girl because his hair is crazy long... He just says I'm a boy, but I have long hair. He doesn't take it badly because he knows there's nothing bad about being assumed to be a girl. That may change as he gets older of course, in which case he can take action to avoid it- but he's happy at the moment.
I'm sure I'm horribly naive, but I just have difficulty understanding what "feeling like the wrong sex" actually means.