Your could also start the paper by just talking about bulimia, not the stats, but what it is. Define it, talk about the symptoms, thing like that.

A “narrative of what happened to you” would not be a proper essay, but just telling a story. Try to really keep in mind that the focus of your essay is not supposed to re-tell details, but your “bump in the road”. Try to come up with one or maybe two situations that really stand out, such as the moment when you realized you needed help or that something was wrong, or the moment when you really felt good for the first time again in a longer while etc.

Stats are something you should, if at all, save for the ending. In the last part of your essay, open up a perspective. You can quote a study about how many girls/boys deal with eating disorders or what the particular reason was for you to slide into bulimia – then definitely keep an eye out for a solution, a perspective, an outlook. Whatever you do, close your essay on a positive, self-assured and focussed note.

Good luck with your essay and admission. =)