Plan B - late period

Sharon

I took a Plan B last month(July) around the 21st I got my period 5 days after. Which was my second period that month( 2 weeks after my regular one). Now it’s been about a month and I haven’t had my period yet. I took a pregnancy test and it was negative. Does Plan B throw off your cycle that much? Or could it be that my periods last month were to close together? 🤔