the condom broke!!

My partner and I had sex a month ago with out a condom and he pulled out but to be safe, I took an EC. This month my period is late by 6 days. I have taken 3 pregnancy tests that have come out negative. I have read that having sex helps your period start, so we had sex and THE CONDOM BROKE!!! So I had to take ANOTHER plan b. 2 plan b's in 2 months...yikes. I have read that plan B can push back your period? Any input? I'm worried to the max. We did have sex a few times this month but we used a confom everytime and he also pulled out. The condom was slipping off but he pulled out and came in the condom so I'm not too worried about that. Please give me some input on what you think might have happened. Do you guys think I'm pregnant?