I have never taken Mirena but I took Depo for several years and when I got off or the occasion when I missed my dose I would have a period and it almost felt like labor pains all over again. My first period was always the shortest one and since I've been "fixed" my period are a lot worse. Everyone's body reacts differently. I would get a home pregnancy test from the dollar store. I know it sounds cheap & unreliable but I found out i was prego w/ all three of mine from a dollar store pregnancy test. Dollar tree carries them. Just in case you wanted to know. Good Luck.