Pregnant on IUD? Please help

I am late by 10 days, normally like clock work and have never been this late. I have the non-hormonal coil got fitted 4 year ago, I have been urnitating alot more than normal and am constipated, I have been more tired than normal, falling asleep in front of the TV, and yesterday I was very peeky and was crying at the slightest thing. I have felt a little quezy and dizzy. My periods normally are very heavy and last from 5 days to 1 week were my last one was very light and only lasted 2-3 days which is very odd for me. I have had slight period cramps but there is zero signs of it coming anytime soon. I took a basic pregnancy test yesterday which came back negative. Has anyone else experienced this? I know there is more chance of a EP with the coil.