I have had my Mirena IUD in for longer than I should, so I guess its expired. Can I get pregnant or have any side effects? I don't know when I will be able to get it removed.

Yes, you can get pregnant if the Mirena has "expired." If you do get pregnant with this device still inside it can present some very serious, even life-threatening, dangers. Please make an appointment to have it removed and/or replaced as soon as possible.