Hello, I am attempting to calculate my due date and I am wondering which date I need to go by. The day I conceived was December 5, 2012, however, the first day of my last menstrual cycle is December 19, 2012. I have kept records of the days that I am fertile and the days I have intercourse with my husband. December 5 is the only date of conception that fits . Do I go by August 28, 2013, or September 28, 2013? Thank you for your help, Joy Norwood