Period didn’t start in placebo week

By period usually comes a couple days before my placebo week but I’m on my placebo day one pill and it hasn’t started. The only way I could be pregnant was earlier if the condom broke with my bf but he went in once and didn’t finish and the other times when he did have a condom and finished in me was if there was a hole but I’m 100% sure there wasn’t.

Midterms is this week so I don’t know if itsbecause of stress or because I’m pregnant