That just goes to show you how people can react differently to the same thing.

Sounds to me CGT that you weren't meant for an IUD right from the start. Some women's bodies try to repel them and to have suffered through all that cramping it sounds like you are one of them.
I have always been diligent about having it removed on time and replaced. The doc who I first went to instilled in me a fear of being able to get pregnant or PID if I wasn't timely in replacing it. It's an easy thing to forget about though.....very easy.

I am looking forward to not needing to use one anymore or any birth control for that matter, but alas it is still not in the cards for me YET!