Have you gotten pregnant while on a birth control pill?

I started my sugar pill for my period week Monday, here it is almost Friday and no period! Normally I'd start late Tuesday or Wednesday. Also my last period was asked, short,maybe 2 1/2 days,it was a very light flow and dark blood.. . Like what you hear people refer to as old blood.

I think I might test tomorrow, but I'm freaked out to see the results. We didn't want to ttc until next month.