What day was the first day of your last period?

Its all very simple count backwards 6 weeks and you'll have your answer! or you can google a conception calander and get a percise dated.

OK. If your 6 weeks pregnant, that means that you conceived 4 weeks ago. You had sex with this other guy, & your husband too close together to truly be able to figure out who the father is.. since tracking your conception won't be a reliable date of accuracy. Truth is, the only way to know who the father is, is to have your husband & baby take a DNA test, after (s)he is born. Good luck.