So the 2ND according to this app iWas suppose to start my Period today marks the 11th iHavent started yet.. Last month my Period was regular my ovulating days iHad sex, now this time iHavent started my period, &&iHave been starting to get cramps like iF I'm going to start &&Nothing.. iVe notice lower back pain &&Sensitive nipples. So itook a Home test Both NEGATIVE.. could anyone help me with what it might be before going to the doctor??