My due date is Dec 3 and based on that my conception date is March 12. I had sex on Feb 26 and again on March 12. I need to know which of these dates could be the correct date I got pregnant. I am confused because I had my LMP on March 7 to March 11 which was a light(spotting)period which I am use to because I have irregular periods. I need to know if I got pregnant as a result of having sex on Feb 26 or on March 12.

You will only have the answer to that question after the DNA test is done to establish paternity. It is impossible to tell who the father is until that time since most of pregnancy is nothing more than a guessing game, even to the most educated.

Ask your doctor. Different calculators are used. But I'd guess March 12. 40 weeks from first day of LMP, or 38 weeks since conception, although 37 weeks is often used and is considered full term. 38 weeks = 266 days = March 12.

I know this old but u got pregnant in march