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Well, it doesn't take a dietitian to know that you are consuming far too few calories. I understand that you don't have the classic symptoms of anorexia, but when someone says to me they like the control they have by limiting calories, I become alarmed.
Instead of focusing on putting weight on, why not try to increase your caloric intake just to have the energy you want. I am sure you are not getting enough protein, carbs and fiber. My calculations are that you are about 112 pounds at 5' 6", which is a little on the light side. How about increasing calories by 100 per day for one week and see how you feel?
It is also of concern that you have missed one period. While it might not be due to anorexia, it most certainly is due to stress
. My suggestion is that you work with a therapist to address your anxiety
and increase your coping skills. Find a cognitive-behavioral therapist. You may find that you need an SSRI medication,also.
There is treatment for this issue, but you need to reach out and see a professional who can work with your anxiety. Please do this for yourself and try to make decisions to be healthy and let the weight take care of itself.
I wish you well and send my warm regards,