Could i be pregnant?

On the 8th my fertile window ended then on the 12th me and my boyfriend had sex using the pull out method. I know you can get pregnant from precum but according to <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> my chances were only 3%. We have used the pull out method when im in my fertile window so i didnt think with only a 3% chance i had to worry. My period was due on the 21st and is now 2 going on 3 days late. I did get sick wednesday but it was just a head cold, idk if that could throw my cycle off. I havent been stressing but I definitely feel off and i plan on testing on the 28th, one week after my missed period.