Will Plan B work for me?

My Bf and I had sex on 8/12, according to <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> I was ovulating that day. I took plan B this morning 8/15. I heard that plan b isn't very effective in over weight women (which I am) and not really effective if I've already ovulated. Will plan b work for me? And if it doesn't work, will it hurt the baby?