Looking for someone

Too keep it short, im looking for a girl that I dated years ago when I was 13, and she was 15 almost 16. I cut things off due to my own mental health problems forcing me too due to my ocd (scrupulosity). She was the only one whose end didn't come from anyone or anything other than myself, and I cant forget her because of that. Ive lost all contact with her for years now and only remember some info aswell as her username on an account thats long been left behind. Ive spent many hours previously searching for her to no avail. Does anyone know any way I could find her? Ive tried almost everything, and I feel like shes the only chance I have left.