In doing some research this arvo....Busymum I thought of you, plus some other info.
You can get the IUD removed & start trying the next day for a baby.
If you want to know if you are going to react to the copper IUD, buy a cheap copper bracelet & wear for a week, no reaction to it not a prob.
The copper IUD can increase your bleeding, the hormone one can decrease it to nothing.
Personally if I was looking at getting an IUD fitted post partum again, I'd go for closer to 8 weeks to allow the cervix to close up more.
It can also take 6 months to a year to settle in