Cooper IUD while breastfeeding

I’m around 2 months postpartum now but a few weeks ago I went in for my 6 week check up. They explain a few birth control options, one being the cooper IUD. The Dr told me I won’t have a period if I breastfed (Once you stop breastfeeding your period will come back) which I’m planning to breastfeed for about a year+ which in this case sounds great. Anyway, I tried to look at some stories on how this is true (bc it’s too good to be true to me), anyone experience something like this? Also, how was the process and did it hurt?