pwede ka pa rin mabuntis sis so its not safe.. not necessarily mas fertile, irregular and unpredictable p kasi yung cycle and ovulation day natin dahil sa imbalance hormone. nauuna ang pagkapal ng matres at lining ng bahay bata bago mag ka regla.kaya hindi excuse n wla pa regla at kakapanganak mo plang unless your doing LAM, pero kung hindi, go to the nearest OB clinic and mag inquire n lng ng best contraceptive para sayo.