Mirena iud

I got my Mirena inserted dec 30 had a period January 20-27 also lots of spotting off and on. Between haven't got my period yet. But everytime me and my bf have sex I bleed (more like a heavy spotting) off and on for a few days, I have had two children which is why I decided to get the Mirena I have no idea what is normal what is not normal I'v read so many bad reviews on it that I'm scared of possibly being pregnant again ( just had my second child 5 months ago) afraid that it could have moved out of place ( I'v been having a lot of cramping for the last few months since I got it incerted.. Just looking to see if anyone eles had been having the same problems as I have being having and was fine ? Or any insight at all would be helpful thanks :)