I had the IUD (Mirena) inserted almost exactly 4 years ago. After insertion I had experienced the usual spotting, but my period has been non-existent for the last 4 years. About three months ago, I got my period for the first time and have been getting it regularly ever since. This is odd because I've never been regular, not once in my life. The flow is not heavy, actually it's quite dark...almost black. I have one more year with my IUD, so why is this changing now? I am not experiencing any discomfort or pain. Has anyone else experienced this?

P.S. I'm 24 years old. Never been pregnant. Have been diagnosed with PCOS. I don't drink or smoke. In the last year I completely changed my lifestyle. So far I've lost 60 pounds, through strength training and a clean diet. Wondering if maybe my lifestyle change is contributing??

Thank you in advance! Any advice is helpful.