Active Systemic Lupus in need of Birth Control

I have a 15-year-old girl with systemic lupus, and psychiatric issues I believe from the Lupus. She has been treated for severe ITP twice (wet purpura, petechiae and heavy menstrual bleeding to hgb 5), and has had bleeding and purpura. She has been on steroids and numerous drugs from her disease including Plaquenil and Belimumab. She has chronic constipation that has required several admissions. She has had bouts of severe itching until she scratches herself until she bleeds and has impressive large purpura. We have been giving her Depo for the last 1.5 yrs because of heavy period. Her medical team is concerned about bone health with all the steroids and Depo Provera. They are suggesting a  subcutaneous implant.  Not sure with her psychiatric component if she would try to scratch the device out. Also, I wanted to confirm from a clotting standpoint that this would be a safe choice. I was wondering if Mirena would give her progesterone, local control of menses without systemic effects, and hopefully, would not be bothered by her propensity to pick scabs and scratch. Yes, she is 15 yrs of age but as you can see she has many other quirks. What is your recommendation for girls with active systemic Lupus who need birth control?