I had my period on July 23 or 24. I had sex on August 3rd, right around day 11/12 of my cycle and the condom came off inside me, but we realized before he actually came so only Pre-Cum got inside. Just to be cautious, I took Plan B about 2 hours later. About 4 days later (on July 7,) I started bleeding. It looked and felt like a normal period but was heavier flow than usual - also lasted the same amount of days as a normal period.

Does the bleeding mean that I am not pregnant? I am concerned because the sex happened so close to my ovulation day.
Also, when should I be expecting my next period?