Roswellmom,
There is more and more research showing that people diagnosed with borderline personality disorder have bipolar disorder instead or in addition to the borderline personality disorder. So especially initially it can be difficult to diagnose, especially if someone is rapid cycling. That being said, bipolar disorder is understood to be more of a biochemical disorder with the swings between moods, sometimes in teenagers manifesting itself with a lot of anger, depression, cutting (which is also a symptom of borderline and is used as a way to calm down and to feel real), or manic impulsive behavior. People with borderline personality disorder frequently were traumatized as a child. It could very well be that the drug use is a byproduct - many people with bipolar disorder struggle with drug or alcohol use or addiction. I would suggest you check out if your local hospitals offer through their behavioral health services what is often called partial outpatient treatment programs. These are covered by insurance usually and provide structured short-term help. Also check with the chemical dependency centers in your area to see if groups are offered for teens.
soleilsun