Help!!! Can Plan B work during ovulation?

So according to eve, my most fertile days are Oct. 7 to Oct. 13. I had protected sex yesterday, Oct. 10, and the condom broke. My boyfriend and I immediately rushed over to the pharmacy to get Plan B and I was able to take it within 15-20 minutes of the accident. On eve it says that I had a 27% chance of pregnancy yesterday and a 33% chance today. I've read some posts online that said Plan b is virtually useless during ovulation. Anyone else have any experiences like this?