OK, without an ultrasound, let's do some old-fashioned counting. Period begins on November 28. Regular 28-day cycles, assume a day-14 ovulation. That brings you to December 12. A woman's egg lasts approximately 24-36 hours. That bring you as far forward as the 14th, if you ovulated in the evening ... on the other hand, it is still within range of the guy on the 9th, since the sex was unprotected. (Pulling out is not much help.