Switched pills

I've been taking a birth control pill for the last two years and this month my doctor and I decided to switch my pill. I finished my last pack, had a "period" and did my Sunday start as I usually do only this time on the new pill. On the 5th and 6th day of this new pill my boyfriend and I had unprotected sex (for the first time). Should I be worried about pregnancy or should I be fine?