Should I take Plan B?

I’ve been using birth control pills for months now never missed a dose. Took it almost the same time everyday. I take it 9:00pm usually although sometimes I come home a little later. So there are days that I take it 9:15 or 9:45pm.

I had sex 3 days ago without a condom and he came inside me. Should I be worried and take plan B now just to be sure?