Can you get pregnant when you are on the dummy pills?

Ive been stressed out a lot over the past few months, and my last pack of birth control, I started my period at least a week early. I was on the third week of the pack for the active pills when I had my period. during the time I should have been on the dummy pills of the birth control pack, I had no period, and had sex. Since then, Ive started a new birth control pack. and went all three weeks (almost... only one day left in the active pills... til I am back on the dummy pills again of this pack) without any bleeding like I had the month prior when I started a week earlier. So Im trying to figure out if it was possible to get pregnant on the dummy pills when I had my period a week prior to that when I was on the active pills.... am I covered still? Or should I worry... ????