Plan B One-Step

Hi girls. So I had sex last night and I always make sure to use a condom no matter what. This time, when he pulled out the condom got stuck inside of me. I freaked out and we went to get the Plan B One Step pill within in 15-20 min. I took it. However, I had never ever taken it before and I am stressing so much. Should I take another one? Please let me know if one pill actually works! This never happened to me.