Y11 daughter dropped out from mainstream school

Please help.

I am an a complete loss. I feel like a failed parent. My daughter is 15 and was privately diagnosed with autism in August 2022 and for at least 12 months have considered home schooling as the school environment is not suitable for my daughter as she has constant meltdowns. If anything it has made her feel useless and like she cannot accomplish anything. School would not accept her private diagnosis and we have been on the waiting list for an NHS diagnosis for 13 months (also ADHD diagnosis).

She struggles with Y7 maths so pushing her through her last year in school and making her sit exams seems pointless She cant get a job due to her age and college wont accept her as she isnt a 'school leaver'. 

Can anyone please offer some advice for options?