IUD Periods

Br
Hi ladies! I get a regular period and I have had my IUD for four years. I was told by my doctor that it is actually quite rare to continue a period on Mirena especially a regular one. Right now, I am five days late. This has only happened one or two times. So any of you get regular periods with Mirena? Does it sometimes go out of wack? Just want to make sure everything is alright with me! I know it's in place because I checked the strings.