Is it possible to be pregnant even if you have not missed a period?

Yes. A woman will ovulate about 14 days before she has a period. If she conceives she will not have a period, and will have been pregnant for about two weeks when her period is due. Conception usually happens within hours of ovulation. A pregnancy test could be positive about seven to ten days after ovulation/conception, which would be four to seven days before her period was due.