hi, i last had my period at the end of july and now i am half way through october and still no period. my last period was just like a quarter size and it was just once and then i didnt have any bleeding after that. i have been very tired lately, have back and shoulder pain,and tender breast (which i only got when i was going to start my period). my boyfriend and i have had unprotected sex but we always tried to be careful, could this mean anything?