My standard advice is that anything can be an effective college application essay topic if written well. Typically, I encourage applicants to write a first draft & then let me evaluate it. My concern in your case is that an on-going psychological disorder which caused you to repeatedly engage in self-harm has almost no chance of helping you get an offer of admission and a high chance of getting your application put in the rejection pile.
I get that this advice is causing you to experience stress and anxiety. Try to write an essay that focuses on positives. Show that you are a hard worker and that you are intellectually curious. Also good to show that you are accepting of differences of opinions and that you appreciate diversity in others. It is okay to share how you deal with stress (hot showers, exercise, mediation,playing with puppies, helping others, etc.), but it is not okay to reveal an ongoing anxiety disorder which causes you to harm yourself if your goal is to get an offer of admission.
P.S. I would like to work with you, but I cannot as I am obligated for the next few weeks on another matter which will consume all of my time. This website–College Confidential–offers an essay review service free of charge. Not sure how to get in touch with the essay writing service, but it is active & it is free.
@compmom is an active participant in the CC essay review / essay assistance group. Please do not stress over writing college application essays as they will guide you in a stress free fashion.