Mirena/iud question!

Danielle • 20* Engaged* & a proud Mommy❤*
Okay so I'm getting the Mirena out in on the 29th.. Kinda nervous lol I'm on the nuvaring right now but I wanted to try the iud. But I've been reading that a lot of women's body's reject the iud??? Has anyone had this experience? I don't want it to make me sick:/ or get toxic shock