When I first got my Mirena, my periods stopped all together except for two very heavy days a month. After 8 months, they started again but were very regular. I have now had it for 2 years and 3 months. I had my period last month but now I am 3 weeks late. I have taken two pregnancy tests, both negative, even though I've not been showing any pregnancy symptoms, which isn't at all different from my last 2 kids.