Birth control (Question at end)

Bailie
So I'm new to the pill first off. This is my first time taking it. But why the hell would the doctor give me a 21 day pack instead of a 28 day pack. I'm not going to remember to take it. Yes I have other medication that I take everyday but that's already become a habit. If I ask the doctor to change it to a 28 day pack will she change it or will it mess up my cycle?