Birth control and plan b

I am a pill club member and for whatever reason I got my shipment late, well 3 days into starting new pack ( norethindrone) boyfriend and I had sex and he came inside of me.

I should be good right? Or should I grab a plan b pill?

I've been on bc for the past 3 months but missed a few days in-between shipments but now I have been back on it for 3 days???