Mirena problems

Alright girls, I’ve had my Mirena in for three years now. It has made my period lighter, come three to five days earlier that expected, and gives me cramps 3 days before it starts. I had spotting two different weeks after my last period and now my period is late three days. Was wondering if this might have to do with my weight gain or if it might be something serious, any advice other than going to the doctor? If my cycle doesn’t start in a few days I’m going to my gyno. Just wondering if it’s nothing to be worried about before I call