The frist one I had on the 13th September in my pants not sure if is important im not due on 16th September and now is 15th September I got this in my pants no hevery bleeding not alot i had sex my last perido was on 19th August came off 21st August been atvice on 1,2,3,4,5,6,7,8,9,10,11, September of having sex and it was on my fertility window please could some one help me and put my mind at rest before I go to the doctor x thank you