Can I be pregnant even though I've had Mirena for 2 years?

I have had the Mirena since July 2007. I have not had a period since September 2007. I am now engaged and my fiancee and I have been having sex unprotected everyday since May 14th 2009. I have 2 children already. I got the IUD placed so that I wouldn't have anymore children until I was ready.

For the past 2 weeks or so I have felt nauseous. I thought if I ate it would get better but it only gets worse. I have increased "wetness" during sex (according to my fiancee). My breast are more "sensitive". I have been craving Ice Cream like crazy. I also cant seem to hold my urine as well as I used to. I went to the doctor Monday(6/8/09) and got a test. They said I was not pregnant. That it was just the hormones, or that it could be too soon to tell.

I'm not sure that test was correct. I have never been nauseous before and it only gets worse after eating. I haven't had a period in 2 years so, I can't use that for a sign.

Help? Should I wait and take another test? I don't want to wait until it's too late and can't get the IUD removed.