there are a lot of considerations here from how much running is "on and off" and what - if any - long term damage you had suffered from the eating disorders

you have a lot of time - I would follow something the couch to 5K plan to get a really easy start to regular training and build up your running tollerances. you can supplement this with cross training and weight training. If you have not already done so - I suggest you talk to a dietician to hel you with your eating.

Once you are running 5K comfortable 3 or 4 times a week - you can start something like Hal Higdons novice half marathon plan