Plan B

So i made a previous post about having unprotected sex and a few of you got back to me about it. Anyway- i has unprotected sex on the last day of my period. I am on birth control but it was the week of my sugar pills. I decided to have my boyfriend pick up plan B just in case-does anyone have any advice on taking that or if i even should take it? I’ve had people tell me i shouldn’t be worried but to just take it to be safe but i’ve read things about plan b saying i’ll have to start a whole new month of birth control or that i’ll heavy bleed? I just got over my period so i’m just very confused and overwhelmed. help?