Hi there. Some women have irregular bleeding the first couple of months when starting birth control. This normally doesn't last long and you go to the predictable pattern you expect from birth control. So, I"d guess this is your body adjusting to the hormones. If you are concerned, you can use a back up method of bc such as condoms but your pill is likely working just trying to normalize with the added hormones of the pill. You can always check in with your doctor to confirm that.