Metabolism destroyed after anorexia?

Last year I suffered from anorexia for about six months. I got down to a dangerous 91 pounds(I was 32 at the time and I'm 5'3"). I finished my hospitalization last July, but I've noticed that I've steadily put on weight since then. I'm currently at 115, which is considered 100 percent of my ideal body weight. The problem is that I don't want to keep gaining to where I'm too heavy. I left the hospital at 100 pounds last July and now I've gained 15 pounds and I'm not sure why. I stopped eating breakfast to cut back and only eat dinner and supper and what I do eat is in small portions and not fatttening at all. I've started walking more, but the weight gain keeps happening in spite of trying to get more exercise in. Is it possible I destroyed my metabolism and that body wants to hold on to whatever I eat and turn it into fat because it's afraid of starving itself again?