Birth control

Patricia

I got the depo shot Nov 5th. It was not done during my period. Dr. Said to wait at least a month before having unprotected sex to allow the BC to kick in. I had unprotected sex on the 1st 2nd and 3rd. I expected my period on the 18th. No period. Pregnancy tests I took last week are all negative. I thought it would take several months before the BC knocked my period off. Could I be pregnant?