Well. My first and most overwhelming thought in regard to your situation is that maybe she needs to get back on medications. Some of her earlier behaviors sound within the normal range of teenage girl angst. Especially with the blended family issues.
I even think that occasional substance use can fall within the normal range. If you look at statistics most high schoolers are dabbling in alcohol and drugs. I don't condone this behavior .. and I believe that it needs to be addressed ... however I don't know that your daughters behaviors are that far out in left field . Teens often go through these things to individuate from the parents.
Same to be said about self injury. Today, cutting is almost in style. How sad is that?
Does she go to therapy? How about family therapy? When a child is acting out, it is rarely just the child who needs 'fixing'. Usually the family dynamics need an overhaul too. The child is usually the presenting family member.
Suggestions? Family therapy. Personal therapy for her. Clear cut and consistent rules. Love her ... it is not easy being a teenage girl today. The pressures are IMMENSE!!!
