Why Am I Experiencing Persistent Vaginal Discomfort?

If you miss a period for more than 3 days, it may be implantation bleeding as well as a medical condition. A gynecologist should be consulted for a thorough examination and diagnosis. The gynecologist or an obstetrician is the best consultant on such conditions.
 

Indeed you can get pregnant if you had sex on the 8th. Sperm can live inside the body for a few days so if ovulation happened shortly after on the 10th then pregnancy could occur. Some symptoms like a missed period tiredness and tenderness of the breasts may start showing. If you suspect that you are pregnant take it easy a home pregnancy test to confirm.

The chances of getting pregnant from oral sex are quite low, but it is not ruled out. The bleeding you may have had after taking the unwanted 72 pill could, indeed, be attributed to the pill itself affecting your menstrual cycle. This can cause spotting or irregular bleeding. Such a thing is not a sign of ovulation bleeding. You can experience a late or early period as well as any of the above. The important thing is to monitor the symptoms enough and give enough time. Recall the pill can throw off your cycle. If you are concerned, be patient, and take a pregnancy test to make sure. Avoid stressing out, because stress can also be why your periods are irregular. 

If you have missed the periods for 10 days but still the pregnancy test is negative, then, the possibility is that you are having a hormonal imbalance or may be some other issues. It needs in person evaluation to proper diagnosis and get the right treatment for you.