I’m so so glad you are getting expert opinions and more resources and figuring out what is going on!! I know this must be so much. But it seems like you are super on the right track and figuring things out, which is amazing. Hang in there!
If homeschooling turns out to be a thing, you might check out to see whether your area has anything like a “charter homeschool” which are these programs where the charter homeschool does oversight of curriculum, etc. so you’re not homeschooling in a void, and are part of a community even if it’s mostly online. Our local charter homeschool even has a sub-program that involves in person classes two days a week, but I think that’s rarer.
I mean, this was totally the case with our ASD kid, who at that age shut down when she was around too many other kids or too much noise. She ended up at a private school with tiny classes and thrived there. But the public schools around here are sufficiently underfunded that basically if a class isn’t stuffed full of kids, they cancel it and shuffle the kids around other places. Sigh. (And actually our private school with tiny classes is chronically short on money and is always teetering on the verge of collapse. Smaller class sizes turn out to be hard to maintain.)