Pregnancy Timeline: Calculating Due Date After Conception

Question
Hello, I have a question I was hoping you could help me with. I was away for two months earlier this year and returned on February 22 of this year, on this day I had sex with my girlfriend and she is now pregnant.  Her due date is on November 4th is this due date about right from the time we had sex?  Reason I ask is I recently found out she was seeing someone else when I was gone and want to make sure this one is mine. Thank you."

Answer
Because she had sex with someone else close to the time of conception, it would be impossible for me to determine whether or not you are the father without additional information.  I would suggest having a paternity test done after the baby is born so that you can know one way or the other.

Good luck!