You are not alone, there are a lot of us.
We went through exactly this, by Y10 & Y11 her attendance was about 10%. She did pass 5 GCSEs, which was good.
She’s 20 now, she has a job at the local pub, she’s at college, she had learned to drive and has a car. Socially / Emotionally I would say she’s about 3 years younger than her chronological age.
Someone who mentioned https://notfineinschool.co.uk/
Please read what they have to say, and reach out to them.
Try not to get stressed, this will all work out .. what your child needs is to know they are safe, they are loved, and you are on their side. I found climbing into her world was good, the best time to have a “proper” chat was when she was playing a video game, or out in the car with music on.
Sertraline was a big game changer for us, and getting her therapy, both of those have been in our lives for the past 4 years.
Its not your job to force her into school, it’s the schools job to make it a safe place for her to attend.
DD is such a lovely young woman now, but she spent about 2 years in her bedroom, and didn’t speak to is for about 12 months of that. I just kept telling her a loved her, and was there for her.