Well now we know how it's working, time to work out why like I said, time for a journal. Make note of anything she does that makes that urge stronger or diminished, even a little. Then you can work on redirection from those triggers, finding things that aren't destructive, but that are enjoyable
Just keep reminding yourself that you can control this, you can keep it in check until you get to see a psych. Do you mind me asking how old you are and how much longer until you can go see doctors without your parents consent or supervision? Because they have tools far beyond what I do, I only have my own experience.