It’s almost impossible to get pregnant during your period. For one most women don’t ovulate during their period. and two everything thats in your uterus is coming out. So sprem would get washed out along with it. But it can still happen so don’t use your period as birth control. Generally if you concieve two weeks later you are 4 weeks along or 1 month and yes you could be having symptoms. When you are pregnant they start keeping track of it from the first day of your last period. So when your 4 weeks along your babies only 2 weeks gestation. Hope this helps you.