I had Mirena inserted in January 07 after the birth of my second ...

I had Mirena inserted in January 07 after the birth of my second son. I am 33 yrs old and have had depression since I was a teen so I didn't relate my symptoms to my Mirena implant. I have been treated with Wellbutrin for about 2 yrs and I have been puzzled because my symptoms have actually increased in the past year. I started researching information about Mirena because initially my breasts were sore and swollen, just like when you first become pregnant. I checked my implant to make sure it was still in place and was horrified to find out that it was gone!! I am going to my OB to have it removed and make sure that I am not pregnant. I do not want more children, I already have 2 sons. I have not seen any reports of pregnancy on this website and I am desperate for some information. If anyone has known about any instances of pregnancy, please, please let me know.