Advice????????

In advance, I know I shouldn’t have had unprotected sex so don’t bash me. I had unprotected sex on Monday the 15th, a day before my fertile window according to my app but my period is very irregular (20-36 days irregular.) my period is “due” in 12 days, possibly earlier and possibly later. I took a plan b after I had sex. The last couple days I’ve had headaches and felt like I’ve had to puke. Is there a possibility I could be pregnant? Again please no hate, just knowledge.