Possible pregnancy on Paragaurd IUD?

So i've had the IUD for about 7 months. It made my period a little heavier than usual and changed from every 29 days to every 33 days, but have still be regular. Well this month i started to cramp and spot on Sunday night. When I woke up mondy the spotting stopped, as did the normal cramping. Now it's Wednesday and still nothing. With my past two pregnancies I didn't have any bleeding or spotting when i missed my period, and the only time i've ever missed, or have ever been late was when I was pregnant, so needless to say I'm a little nervous. I have a 2 yr 3 mth old and a 9 month old so I'm not really ready for another one, if ever, thats why I got the iud. Has anyone else experienced something similar and if they turned out pregnant or not. Thanks