Pregnant?

So my boyfriend and I had sex on 3 days during my fertile week, using just the pull out method as our birth control. Everytime we had sex, we had a second round within minutes of each other, and he didn't pee before the second round. I had sex on May 17th, 19th, and 21st. My period is supposed to come on the 8th... I know it's too early to know but it's killing me, could I be pregnant? How likely is it?