Well, the Dx would be for whatever the current situation is.
All current disorders would be listed, with the appropriate code numbers. Somewhere on the form there usually is a place to mark which is considered primary disorder - that is the one that most impacts your life and is the primary focus of treatment. All disorders combined would be considered your disagnosis. Again, depending on the form, and it's purpose (insurance, internal agency thing, etc.) there would be some other place to put info on your history of an eating disorder, and whatever of details are needed)