Caring for daughter with severe anxiety and depression who is mostly housebound

I am a single mum to three children. Two sons and one daughter. My daughter is 18, she's a creative, funny, and intelligent young woman and was capable up until a few years ago, well at the start of high school I started to see the change. She started to get more reserved, started isolating more especially after a series of bullying events and her father moving and remarrying. She'd focus more and more on her phone, her looks and kept making bad choice after bad choice. She lives with me full time and doesn't see her father as he has abused her in the past and rarely makes contact or tries to see her yet continues a strong relationship with her brother.

Throughout high school there was a lot of school refusal to the point that she was barely attending in Year 12. She's tried to push through many milestones and actually managed to get her high school certificate and attend the school formal and earlier this year got her licence on the first go.

Fast foward to now where she is completely isolating spending almost 24 hours per day in her room.

Currently she is undergoing ADHD testing with a psychologist and will be seeing a psychiatrist soon for help with medications etc.

I have come here to try to find people going through similar as I feel so unbelievably alone in this.