Chances of being pregnant?

My last period was dec 20-23rd. My boyfriend and I had unprotected sex the day before my period, the last day of my period, and on the 26th and 27th. My fertile period according to glow is dec 31st-Jan 6th. Is it possible I could get pregnant? How soon can I know? Thought we were safe cause of my period and not being in the fertile week.