So much of what you've described sounds like how my autistic DD was too. School described her as fine, happy, chatty and bubbly. It took me YEARS to realise she is not chatty at all at home, and this whole bubbly persona was her masking. It ended badly for us, totally burnt out by Y6 (and I mean autistic burnout, so regression in multiple areas, washing, dressing, communicating, accessing hobbies, unable to attend school, became mostly housebound and still recovering/struggling 2 years on).
This was despite school agreeing child was autistic, them speaking to us about various struggles (friendships, "being very rude without meaning to be" I.e direct autistic communication, black and white understanding, struggling to follow instructions in class) and then an NHS diagnosis the standard few years later. Hence why there wasn't enough support by half until DD hit crisis, and then there were lots of accommodations made.
DD is also diagnosed combined type ADHD via CAMHS.
She is bright, did used to seem outgoing, would talk to anyone, had various hobbies. It took me a good long while and 3 years of school hinting to twig they meant autism as girls mask so well ans present so differently.
Go to the GP. Rule out other physical causes. Maybe look again at autism. I could have written so much of your posts! Except social skill differences were clear with my DD, but I just thought she was quirky. And dyspraxic.