well, I would say that even though you don't feel hungry, the fact that you havent'eaten in 4 days would indicate that you should. And having an ED you system is just out of wack from your different eating behaviours. When you start eating on a regular basis your body should slowly start to tell you what you need again.
I really think you need to get some help. I can see that you are hurting from the number of posts you have put on here and the content. Please find someone to help support you.

The longer you don't eat the more your brain will ignore the fact that your stomach is hungry. I know how hard this is because I am in the same boat! Try and eat just a few small bites of something throughout the day and drink water to keep yourself going. Are you seeing a therapist and nutritionist? I started awhile ago and it has really helped, even though it is very hard to open up to someone.... Good luck:)