weight help?!

Ch
so im 20 and 5'1. i weigh 91.2lbs. i found out that my ideal weight should be around 118lbs. i was anorexic then bulimic for a year and a half, and since then i physically cant put weight on no matter how much or what i eat. i've been on various supplements and vitamins and diets from various doctors,but nothing works. does anyone know any ways i can get to a healthy weight??