She sounds very anxious, OP, and schools aren't usually good at dealing with anything different. You're simply expected to keep your head down and get on with things, and if the wheels fall off, then you will be off-rolled or encouraged to leave so that you don't affect their results 🙄Schools are far too big, and I've heard them referred to as being like sausage factories before, just churning out students who were able to conform and make it to the end. Do you have any colleges that offer courses to home educated students, or to children who can't be in school for some reason? There is also book called 'Beautiful Failures' by Lucy Clark, which resonated a lot with me.
Does she find people overwhelming and anxiety-inducing? Her bedroom is quiet, and it is her safe place, where she can recharge. Also, siblings can be genuinely annoying, especially if you're two very different people being forced to live under the same roof!
My mother said that I was harder to raise than my brother. He was the 'normal' one who went through school, sixth form, passing his driving test, university and getting a job at all of the normal ages and without any serious problems. I found all of that, coupled with family pressure and teenage hormones, too much to cope with at the time. I did do all of those things, just at a little bit of a later stage, and with a nervous breakdown along the way... and still spent all of my time in bed, because the world was too draining, and I didn't have anything to get up for. My family backed off with some of the pressure after the breakdown. I went to a smaller, more vocational college with a relaxed vibe. I got a puppy, who gave me the reason to get up in the morning, and a lot more besides. I got a job with more animals than people. That job, fortunately, came with accommodation, so I live very rurally, where it is quiet and there aren't many people.
Anyway, sorry for the long post, but it does get better, OP. It takes a lot of mistakes and successes, and when you're 14, you can't see this. All you get is, "Your schooldays are the best days of your life!" and at 14, you think, "You mean it's going to get worse...?" which isn't exactly motivational!