Maybe social services is a bit of a drastic move to make right away. It sounds like you're going through a heck of a lot with your step daughter, though, and I can understand that this would be extremely frustrating, especially when you are doing your best in the situation, so, as you mentioned, it may be a good idea to involve someone else. Maybe since your stepdaughter seems to have a positive attitude towards school you could speak with her school counsellor. The counsellor may be able to speak to your stepdaughter at school and help her to express how she feels, and also work with your whole family to ease things at home. I wish you all the very best!