Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned with eating disorder(probably anorexia nervosa) and its effect on menarche.
The onset of anorexia nervosa (AN) during childhood can affect the timing of puberty. The first period may be late because of many cases of amenorrhea including anorexia. You must consult your psychiatrist for detailed evaluation and questionnaires to establish the diagnosis of eating disorder as the same cannot be made online and start appropriate remedial measures.
Hope this helps. Take care.