Can you get pregnant with having an IUD?

On top of that I am overweight. Everyone believes I am pregnant, but my belly isn't getting hard like most pregnant women and I don't seem to be having any of the normal symptoms. I am told that not all heavy women who get pregnant have a hard belly from pregnancy. I know that I need to speak with my doctor, but can pregnancy happen 1) with an IUD in, 2) without my belly getting hard and 3) without most of the normal symptoms?