OP and everyone going through this, you have my every sympathy. If it gives you hope, my DD is now back in school for 6th form and is happier. The school have made many accommodations for ASD (diagnosed last year) after a hellish time in Y10 and Y11 where at the lowest point, she essentially shutdown, barely went to school or ate for 6 months.
It was without a doubt the most stressful period of my life (and I include losing a parent during COVID lockdown).
If I had read the judgemental and ill informed posts on this thread when she was like that, it would have really compounded the feelings of guilt, shame and frustration of not being able to get her into school.
@BoldPinkPoster for us, working with the school was key in getting a reduced timetable, work sent home and various other accommodations made in order for her to access her education.
She also accessed private counselling, but I know that is not easily available to everyone.
We are fortunate and have found the school to be keen to support even if the resources are stretched. Building a good relationship between us (parents and DD) and HoY, SENCO and Attendance Officer has been key.
I wish you well - this book was really helpful, she has written others too.
Can't Not Won't: A Story About A Child Who Couldn't Go To School https://g.co/kgs/jzoSEUe