OP, kindly, you need to take the heat out of your reaction. It won't help.
My ASC daughter has been gay, a trans boy and is now bi. She has been a he, a they and back to a she. She has had various names in her teenage years. We all just went with the flow. I can't say I wasn't worried at times, not because I would mind if she became a he (at all), but because at this age (she's 14) it's so fluid, partic as a ND child.
She now has a very strong sense of who she is. Although life as an ASC teen is SUPER tough she no longer worries about her identity.
She has that because we've had open conversations throughout, I haven't belittled or disregarded how she felt and feels, and we had some really good, honest support from CAMHS. We've also had the most grown-up nuanced conversations about gender identity, which tbh a lot of so-called grown-ups could learn from. It has been a process of open, honest exploration for us both.
Your DD is trying to find her place in a confusing world. Support her rather than fight her - and it's highly likely the outcome will not only be a happier child, it'll be an identity that you feel OK with.