Easter 2012 will fall on April 8, so as of December 1 you will have 129 days to wait.
Thank you for the birthday wishes. I appreciate your kindness. Today is World AIDS Day, so let's also take a moment to raise awareness about this important cause.
Based on the dates provided, it's unlikely that you could be the biological father. A typical menstrual cycle would suggest that ovulation, and thus the most likely time for conception, would occur around mid-cycle, approximately two weeks after her last period on November 10. Since the child was born on August 10, the conception would likely have occurred in late November or December, which does not align with your sexual encounter on December 1.