I started birth control 2-3 weeks after my period was over, i just got to the last week of pills but i haven't gotten my period yet, is that normal, also i had sex before i started a few times but rlly unlikely that i'm pregnant?

Unprotected?: First do a home pregnancy test. Next, your BC pills should be taken on the first day of your cycle or begin 5 days after the start. You are not retroactively effective and you will not be protected until you have finished 1 entire pack of pills. Additionally, FYI, you should always use condoms if not protected by pills to prevent STDs.