HELP, BC

Okay, so I've been on the pill for a few months now, but I couldn't afford it during my last cycle (January), so I didn't take it at all. This month though, I got it refilled. My period started on the 30th and ended on either the 3rd or 4th. As soon as my period ends, I have about 28 days before it comes again. The fertility tracker on here says that I should ovulate between the 12th and the 18th. Tonight, I had protected sex with my boyfriend, but the condom broke. I was wondering how likely it is that I become pregnant, if I'll have to take Plan B. Thank you, ladies! (today is 2/7)