answer:Is this your first pack of pills? The pill affects your hormone levels and suppresses ovulation. However, hormone levels take a while to adjust. If I’m not mistaken, “they” say that you should assume it won’t be effective for the first three months. It’s said that, when taken correctly (which it sounds like you’ve been doing), birth control pills are about 97% effective. If you’re really that worried, the “morning after pill” is an option. I know that in Canada you can get it from a pharmacist; I’m not sure what the system is like in the US but I believe it’s similar.