Late period with Copper

I got a copper IUD in October. Ever since then I’ve been randomly cramping and spotting, and my periods in October and November were heavy, lengthy, with super intense cramping. I know this is expected, the problem is I’m now a day late for my December period! I’ve had cramping and have been emotional, but nothing else. This is also my first time off birth control for 13 years, so I know my body is also figuring out its regularity (right?) other thing to add is I’m underweight, so not sure if that has anything to do with it?! Never thought I’d be HOPING for a period!