Great article and I feel we were meant to find each other on this one. Struggling with severe depression at 12, cutting myself, and now working in the mental health field I can say majority of issues are environmental. Something in the environment is too chaotic and cutting does become a form of control. I do believe antidepressants work and have taken them as an adult.
But, I do have reservations with kids under 18 being on them just because of ongoing brain development. Antidepressants should be last resort after working on weekly therapy, working on issues in the home and at school, and development a supportive network for the child with friends, family, and professionals.
Because your daughter was doing well in school and seemed to try it out of curiousity, I honestly believe things will be alright with her.