I was expecting my period on the 14th. on the 9th, 11dpo, i began bleeding. it was light then heavy. now bleeding is gone. what can this be?

Probably nothing: Menstrual cycles can be irregular due to many factors (stress, diet changes, weight loss or gain, medications, strenuous exercise, etc). Having an occasional period that is not when expected is fine. Keep a calendar of when you have bleeding and menstrual symptoms (breast tenderness, cramping, etc). You will likely see some variations.