Well only a professional can diagnose but she sounds like Borderline Personality Disorder. I mean half of the youth with similar problems that I know who were Opposition Defiant as kids were diagnosed with BPD later on (though if ADHD is also present, it is often missed).
I have a lot of personal experiences helping children and youth from extreme backgrounds and with extreme behaviour problems. I am not a professional, but I am heavily involved in the lives of 8 youth that were, when that age, COMPLETELY out of control. Most of them however now are adults.
The youth I dealt with around that age were doing hard drugs, running away from place to place (one youth had slept with over 50 men by the time she turned 14), threatening each other with weapons and knives. Physical fights, breaking stuff, either not attending school or expelled for severe behavior.
Two of the girls who were living with me at 13 and 14, they had a fight over a hairbrush when I was out for an hour, I came back and 3 windows were smashed completely, the TV, and various other things were broken to pieces.
Most of them were arrested various times etc, and the smallest thing would cause a MASSIVE emotional explosion, typically anger and aggression. Some of them made serious suicide type attempts.
I have had heavy objects thrown into my head, on one occasion they managed to kick the door off the hinges and it cracked me in the head- hard. I've been kicked, spat on, you name it.
All of these youth are doing much better these days. Most of them are employed or studying.
Certainly I think professional treatment and oversight is desirable, but my philosophy has been love and tolerance.
They always knew I loved them, no matter what they did. I always stuck by them, and always forgave them whatever they did, because I could always see the good in them.
I have found with out of control youth of that age, you need to minimize rules and pressures to the basic essentials, and its critical to stay calm. Oh I am not saying its easy, I have been so stressed, I have memories of hyperventilating and shaking with stress.
Love and tolerance I think are the most important things you can give such youth.
Medication however (under the supervision of a medical professional) may also be very important. I mean I take medication myself, I have been diagnosed ADHD and Borderline Personality Disorder combined.
Oh one very important thing I have learned is to constantly validate and reinforce the GOOD you see in such youth. I think strict, authoritarian or angry mindsets towards youth with such problems to be counterproductive.
Also with the RIGHT support in place, I mean 13 and 14 and even 15 tend to be the worst years, all the youth I know started to improve around 16-17.
Just my views and experience, that's all. If you don't agree with me, fine, if you want to talk PM me
BTW I was one of those out of control youth myself, believe me, I was an absolute NIGHTMARE as a child and teenager, but now I try to support others with severe emotional/behaviour problems, living with two of the youth I mentioned at the moment (both are now adults, and doing well).
Ok just to babble on, what was I like as a teenager?
I tried to carbon monoxide myself in a car at age 13, and was detained in a psychiatric hospital the day before my birthday when I had the full intention of throwing myself in front of a train.
I destroyed all photos of myself, and all of my possessions. My father challenged me, and I utterly smashed to bits his expensive car, broke every window in the house, kicked dozens of holes in the wall, and tried to kill with with an axe from the backyard.
I am not at all violent or out of control these days, I have seen some of the most completely messed up people gradually turn their lives around. Helping others was what helped me the most, personally.