The resumption of a regular period or returning to a pre-eating disorder weight in no way tells us that someone is weight restored or energy balanced just yet. While they are great signs that things are moving in the right direction, it takes about 18 months to reach a solid remission from a restrictive eating disorder.
You are liable to simply shift your eating disorder from to anorexia athletica if you reintroduce exercise. Please re-read Phases of Recovery from a Restrictive Eating Disorder and specifically search for the sub-headings: No Exercise, Honeymoon, Menstruation and Knowing When You Can Trust Your Hunger Cues.
And more specifically, please read Exercise II: Insidious Activity to understand why the resumption of exercise has tremendous pitfalls and problems for those with restrictive eating disorders.