Hi and welcome to DWD.
Sweetheart you're 14. This isn't something that you can deal with alone. It's not something that people much older than you would need help with.
It sounds like you are doing as much as you can and that's really brilliant. Do you know why the counselling didn't help? If she can't talk to her parents, is there a member of staff who might be able to help or have you broken up for the holidays?
Is she able to go to her GP and ask them for help - maybe you could go with her?

Do you have the numbers for things like Childline and the Samaritans?