Late period

According to the app my period is 4 days late. My ex and I hooked up about a day after my last period ended. I took a EC plan b. A week later I had some spotting. We ended up hooking up again a few days after I was done spotting unprotected. He pulled out, but now my period is late. I’ve been having sore boobs and some mild cramping. Could this be pms or is there a chance I’m finally pregnant? I know the EC can delay your periods.