Birth control IUD

At my 8 week pp appointment I decided to get the mariena since I'm breastfeeding I did my research first and the reviews kinda equalled out ... but anywho I've been bleeding since and it's not heavy it more like a light period but it's been a month since I've gotten I went in to my ob who said it's normal it's just my body adjusting to it and that it can take up to 3 months before it stops... has anyone else experience this whose gotten it or had it before???