WORRIED, HELP ME!!!!!!!!!!!!!!!?

I have been using tri sprintec 28 day regimen birth control for 2 weeks and 4 days. On the instructions that come with the birth control, it says, "use a backup method such as condoms for the first 7 days of use." On about the 13th day of use, I had without a condom, and he finished inside of me. Should I worry about being pregnant? Was the birth control effective enough?