Emergency! Plan B?

I had the bright idea of having unprotected sex. He pulled out, but when I asked him if he came in me he said, "I don't think so." And OF COURSE I got on Glow right after to find out that I was supposed to be ovulating that day. I'm just wondering if Plan B would even have give me a chance? I was reading other posts about Plan B and saw something about it won't work after you've already ovulated? Just confused and need a little light! :(