Also just so you know with mine the test always showed up a very faint positive, I never had a bright positive.
I agree you probably overdid it but yes you can get pregnant on the Mirena iud I did after a year and it was still in place.
i would take a test to be sure, if not maybe you just worked your body to hard i do know that the longer you have mirena the less effective it become. i just had mine removed last friday.