Ineed Help :( Today I Had Sex With My Girlfriend

Ineed help :( today i had sex with my girlfriend and she was discharging but when i looked at her first response calender on her phone ,yesterday was the last day of ovulation sooo last minute during sex ithink the condom broke and a lil bit of sperm got inside if her . And ik females are very fertile during ovulation sooo we immediatly went to rite aid and got plan b in know less than 30 min. And she took it right away .. Should we be worried :( we've had a incident like this before