Please go to a doctor who specializes in eating disorders. You are certainly not alone, but this type of disease makes you feel as if you are. You need to let go of the emotional control binging and purging has on you, and to do it with someone who knows the best way to go about it.
You are so much more than the number on a scale. You are a human being who deserves to live life to its fullest, and you are not doing that right now. Go back to the hospital and tell them you're not coping well and you need help. Please come back to the boards and post often, we're all here for you.