birth control questions!!

Gwen • Gwen. 19. Aspirations of saving the world, but currently a small city pizza maker who`s obsessed with dogs and lizards
so I started taking the birth control pill, and it is supposed to make it so that you don't have your period all month other than the 4 pills at the end. I'm on the second week (should not be getting my period for another 2 weeks) and i started it 2 days ago. Does anyone know why this is happening?