IUD stopped my period.

Sarah
Hi, 
I am new to the Mirena IUD and I just wanted to know if anyone else has had their period stop because of it. I'm still getting the same symptoms of my period just no bleeding. I guess it stresses me out because I don't know if I'm pregnant or not. I took a pregnancy test and it was negative but I'm still nervous. 
If you have Mirena, how long did it take for you to stop your period and also what are the chances of pregnancy on it?