Warning: R rated. Expulsion?

Im going to be getting an Iud. I cant remember the name but its a smaller version of Mirena. This is where it gets personal, my boyfriend is pulling 6 and a half inches (alot for me since i have an unusally short vag) and we also have very rough sex (i have a pain kink so often to the point of ramming up on my cervix) i need an honest answer on how much this will affect the risks and placement of my iud?