Plan b confusion!

Holly • 23 • mama to two beautiful bby girls • engaged

My hubby and I had unprotected sex last night and he didn’t pull out in time ik pull out game weak. Lol. So I wasn’t sure if I was ovulating or not so I took an opk in the morning which was positive/peak. I’m 5 month postpartum currently and we aren’t against having another right now but I was looking into the plan b just to understand all my options. My question is does the plan b still effective if your already ovulating?! I was reading online that it’s not.