Plan B during ovulation?

So I had unprotected sex with my bf and he came in me. I took the pill within 12 hours of the unprotected sex. However, I heard that when you are ovulating, Plan B becomes ineffective. I do have a Kyleena IUD as well so I don’t really get “periods”. I have a week or two with light bleeding but never real periods. How would I know with an IUD if I am ovulating or does that not apply for me?