Period irregular

I've had my IUD since July. I have had some spotting here and there but no period for October. I thought I was going to start yesterday because I had spotting and cramps and was very tired. But I didn't. Anyone else experience this? Is my body turning off the period function after only a few months? Are my cycles just going to be longer? I was freaking out a couple weeks ago when I was supposed to have a period. It's never been this late. Now I am sure it's just the IUD doing its thing.