Pregnant on iud

Anyone on here that got pregnant on the Mirena iud? Was it viable or did you lose it? I don't think I'm pregnant but I've just been feeling off lately. I took a cheapy 88c walmart test 2ish weeks ago that was negative. And I know the chances of it happening are low which why I'm pretty sure I'm not. Not that it would be unwanted, but we were waiting to start trying for number 2 till the end of the year. Since having the iud in ive not been very regular so its hard to track when my period is supposed to arrive