Hi OP
I have been in exactly the same position with DD. She’s 17 now and we have just had her Autism diagnosis via CAMHS, and through that she has a consultant psychiatrist, who also thinks she might have ADHD so we are going through the tests for that.
She missed all of Y10, all of Y11 (did go in for exams and managed to get 5), she has missed the first year at college, and we are “fingers crossed” for this September.
I went through all the feelings you are having .. rage, anger, despair. How could my child just refuse to go?, why were the punishments not making her go? We were also dealing with quite violent “meltdowns” … I can’t tell you how unhealthy this household was.
So I decided to change his I felt about it … I made a list of the things I could do, instead of worrying about things I could not change. I could not force my child to go to school, regardless of how much I tried (and shouted and cried) so I stopped doing it. Took all the pressure away. This is not her one and only chance to get qualifications, you can study at any point in you life, what was important was her mental health.
My focus became getting her what are needed … I have had complaints into PALS, The Mental Health Trust, The Council - one thing I would say is to get good at complaining. You are your daughters greatest advocate. I found the best thing I ever said to my daughter was “I’m on your side”
Keep her on the school role … tell them, and the council, you are more than happy to go to court and list all the times you have asked for support - trust me they will change thier tune.
SS will give you nothing, she’s not at any risk.
Please take the pressure off yourself to get her into school, there are teams of professionals who’s job this is, your job is to be her mum .. that calm, steady and solid place in her life.