breastfeeding can throw your cycle off, so it itself is not a good form of birth control. even if you know your body very well, you can be easily fooled. you can still ovulate even if you haven't gotten your period. my own experience, i have gotten pregnant twice while breastfeeding, the second time while using birth contol in addition. so if you're trying to avoid pregnancy, i would just use bc every time, and if you're trying to get pregnant, i would throw caution to the wind, forget about indicators, and have fun.