I 2nd what shezbut has said except for being below normal weight. In addition I've always had a low appetite & when I get severely depressed I don't allow myself to eat or when I get very upset I tend to make myself go to bed without eating. I don't think it's linked to an eating disorder, but it really does sound like you are very depressed.

Do you have a good support system? Someone you can reach out to for help in times like this?