Sounds like your main defense is to shut down. You shut down emotionally so you feel very little; physically, so you don't eat; spatially so you limit your environment to a small place.
Smallness and isolation is a comfort to you. It's a comfort that isn't working for you. It's a comfort that allows you to remain in a place where you do not develop or gain strength. You maintain the status quo or get worse if you believe that more smallness and more isolation are your only ways of coping with life.
But, the problem, such a part of anorexia symptoms, is that you cannot get small enough or isolated enough to stop being a human being. Feelings will get through, and you believe you cannot cope with challenges life will present except through shutting down. This has got to lead you to anxiety.
I recommend any kind of regular practice that invites you to open. For example, you might explore open heart loving kindness meditations.
When you know shutting down doesn't work for you and when you know you can't get small enough to be safe, then you have to turn your ship and head out into a larger world. You move away from isolation toward relationships. You pull out from smallness and allow yourself to grow into your true size. You do this slowly and gently, but you do it daily, like it or not.
You can want something and learn that you can't have it. You function anyway. So when you want to be alone, that may well be your cue to open more and let yourself be more visible and present. That's how you encourage your own development and healing. Your therapist can help with this. Make sense to you?