I Have Just Started Taking Cilest. I Took The Last

I have just started taking Cilest. i took the last pill of my first pack last Friday, and have not started a period yet. I did not miss a pill and I started taking the pack on the first day of my period so they should have been of maximum effectiveness.

As its my first time taking them I'm a little anxious about trusting them. If I don't have a period during these 7 days where I'm not taking a pill, could I be pregnant?