Period problem

Patient: Good day!i would like to ask if there is a tendency if i can be pregnant? my boyfriend and i had sex last december 2011, we used condom, after 3 days i got my period, but the next month. january2012 i missed my period. i was confused because my period is also irregular, thats why i dont know if there is a tendency that i am pregnant? please help me. its now feb 5 2012 yet i dont have my period