D.P.
Do you think she could have oppositional Defiant Disorder (ODD)? Is she getting therapy? I don't know what to suggest except to continue to get her to therapy.
Could you take her to a home/program for single mothers/homeless women and have her spend the day so she can see first hand how tough it is to be in the position of having to support oneself without an education/vocational skill?
Have you seen the 30 Days tv show about living on minimum wage? It might be an eye opener for her.