Light Bleeding After Plan B?

I had unprotected sex last Sunday, and took a Plan B pill about 6 hours later. According to this app my period is a day late (which it’s almost always a few days late from when eve tells me I should get it). Starting yesterday I’ve had a little bit of spotting and light bleeding which isn’t normal for me at all, but I read that this could happen after taking the pill. So, is this my period (just extremely light) or just spotting from the pill?