My period finally came. it was late. i'm on birth control. i have 2 placebo pills left in this pack. should i start a new pack on schedule or wait until this period ends to start the new pack? this is my 3rd cycle on this pill, last two were normal?

In this case, if bleeding still persists, starting a new pack may stop the withdrawal bleeding, but if bleeding persists, on the new pack, stop for an additional five days and then restart the remainder of the new pack according to prescribed directions.

This is only a minor delay of your period. Keep in mind that the withdrawal bleeding on the birth control pill is not a real period so the timing is less significant, and sometimes it does not occur at all. Stick to your normal schedule and do not make adjustments based on when you have bleeding.