Is Taking Birth Control Pill Sufficient To Avoid Pregnancy?

hi, my boyfriend and i had unprotected sex three weeks after the first day of my last cycle. im not on the pill but i did take the morning after pill aproximately 36 hours after intercourse. this was 2 weeks ago and now im a week late. i have been exercising more lately and i did have a binge drink or two. i am currently a student and will take the test shortly. the question is... how worried should i be?