Could I Be Pregnant If My Contraceptive Injection Was A Day Late And When My Period Is Now 4 Days Late?

Good day! supposedly i was injected on March 18 but instead i was injected March 19 and i had unprotected sex that night. That was my 5th time to take injectable pills. i was expecting to have my period on April 1. my last 3 cycles was 27 days. I haven t got my period yet so it is already 4 days delayed. I m not yet ready to get pregnant please help me thank you.