Pregnancy Possibility: Late Period & Negative Tests

Question
I am 21 years old. And I have no children. My last menstrual period was from March 4-10, 2006. My cycle usually runs between 28-32 days. I did have intercours on March 18, 06 using withdrawal method, and now my period is over a week late, but I took 2 hpt and both were negative. Could I still be pregnant?

Answer
If you have a 28-32 day cycle, ovulation occurs on cycle day #14-18. If your last period started on March 4, you would have ovulated between March 17-21. You could have conceived if you had unprotected sex between March 13-23. A pregnancy test will not show a positive result until 14-21 days after conception. The best time to take a pregnancy test is seven days after missing your next period. You were due for your period on March 31-April 4. The best time to take a pregnancy test is seven days after missing your period. If you do not get your period by April 11, take a pregnancy test. If the pregnancy tests are negative, it is doubtful that you are pregnant. If you have doubts, take a blood test for pregnancy. NEVER use the withdrawal method. It does not work at all. There are around 300,000 sperm at the tip of the penis prior to ejaculation. If you try to withdraw prior to ejaculation, these sperm can be milked into the vagina and, if it is at your fertile time of the month, you can conceive.