Pregnant on birth control???

Andrea
Ladiesssss , have any of you ever gotten pregnant while on birth control PILLS? Also are your periods light or heavy?? 
I've had some random cravings and when I had my first period since baby I "bled" maybe twice while on it. Was really weird. It's my first time taking pills and I set an alarm to take them at the first time every day lol I don't wanna slip up.