I, too, have been diagnosed with ED-NOS with ana tendencies. I am also small framed and feel like if I weigh over X amount then I will be fat. However, I look at pictures of myself in my very un-healthy days and think to myself how disgusting I look because I am so skinny in those pictures. I am not happy no matter how thin or healthy I am. It is something that I am working on with therapists and a dietician.

You don't have to have been hospitalized for an ED in order to have one. Just like many people have never been hospitalized for depression, and still are diagnosed as depressed.
ED-NOS just means you don't fit the criteria for Anorexia or Bulimia. If you want a more thorough description, ask you psychiatrist or therapist.