Advice please!!!!

Okay so i had protected sex on July 31st (8th day of my cycle) my period started on july 24th. We had a freak out moment bc we thought the condom broke bc i rubbed some white fluid off but when he pulled out it looked like cum was staying put in the tip of the condom. Out of freaking out, i took a plan b pill the next day about 16 hours later. I keep freaking out bc i CANNOT be pregnant. Am i overreacting or what? Advice please!