You could still be/get pregnant. The "pull-out" method is no kind of method to prevent pregnancy because there is sperm in the precum. The youngest documented pregnancy is a girl who was 5 years old, so anything is possible. Some women ovulate during their period, so you can even get pregnant while STILL having your period. If you end up missing your period, I would definitely take a home test and find out. Look out for symptoms such as breast/nipple tenderness, nausea /vomiting, frequent urination, etc.