Could Delayed Periods Be Due To Pregnancy?

Hi. I am regularly taking Nordette 21 as OCP since November. My boyfriend and I is using pulling out as well until December. This January, we had sex last Jan. 4 (4th day of my pack 3) and Jan 18 where he both came inside me. Now, it's been two days after my last pill and I dont have any sign of withdrawal bleeding. Is it normal or there's a possibility that I am pregnant? Should I continue my next pack of Nordette this 29th even I don't have withdrawal bleeding? Thanks!