How are you 3 weeks and four days pregnant if your fiance ejaculated in just 12 ago?

It is not possible to be three weeks and four days pregnant if your fiancé ejaculated inside you just twelve days ago. Pregnancy is calculated from the first day of your last menstrual period, not from the day of conception. Conception typically occurs about two weeks after the start of your last period, and it can take several days for the fertilized egg to implant in your uterus. Therefore, you would be about two weeks and four days pregnant, not three weeks and four days pregnant.