Is Pregnancy Possible While On Althea Pills?

Hi. I ve been regularly using althea pills as contraception. I just had a bit of an unexpected intercourse. I am on my 5th day of taking the pills right after the 7-pill free days. On that day, i had unprotected sex. My question, is it possible for me to get pregnant? Am i still protected on that 5th pill? Im a bit worried. I am still continuing to take the remaining pills now and am on my 13th pill today. Hope you can answer my question. Thanks :)