Could Alcohol Cause Delayed Periods?

ok. im 19 and a month ago i had unprotected sex but the guy never finished, ( we got interupted) that was the last week in that month.. th very next month i had protected sex and also got alcohol posioning...i didnt get my period in that month and i took three pregnancy test for each of the three weeks left in the month and they all said negative... not its a month and i still havent gotten my period. i was wondering if the alcohol could of made me skip a period or if there is a possibility that i could be pregnant...?