Hi,
If you read the book "myth of Laziness" by Mel Levine it might give you some insight on why she is stuck. I am guessing you have tried medications, going to a psychologist or social worker, checking her blood work for any physical issues, give her vitamins and fish oils, be sure she is sleeping okay, checked her for sensory issues, considered some of the alternative therapies out there.
I bet you have tried to get in her head to see what is going on and determine what is holding her back. Does she suffer with depression? or ADHD? I just learned last year that research shows that kiddo with ADHD are 3 years immature for her age. If this is her issue she may just need time to mature.
Most of the reading I have done says when you punish by taking things away it just puts up more walls and pushes them away. You don't need her to run away either or shack up with some guy.
My daughter is similar in a lot of ways but she is in school, she finally has done much better with Adderall. She is finally beginning to grow up little by little but I now realize she may have Asperger's Syndrome.
Wishing you well-Love her, Praise what she is doing right and go to professionals for help is my opinion. Step in her shoes,
As Ross says, "Children do well if they can"
As I say, "I am only as happy as my saddest child"