Help - could I be pregnant?

I was taking the progesterone-only pill for a short while in December. Me and my partner had sex and he came inside me. A few days after this, I stopped taking the pill. I’m worried as my period hasn’t come yet, it’s 8 days late and my pill worked in a way that you could get pregnant immediately after stopping it. Has this type of period irregularity happened to anyone else in this situation? And what are the chances I could be pregnant? As I’ve read sperm can live up to 5 days inside. And I didn’t get a proper withdrawal bleed like I usually do. I am freaking out.