IUD and period

So today is officially three months that I've had my Skyla IUD put in. My period comes at the same time every month. I Started my period three days ago and it started a day early with intense cramps and I had been spotting for about a week and a half prior. I had some light bright red blood and then the next morning I had a huge chunk of uterine lining come out but no blood! I'm so confused because I'm used to bleeding and now it's barely there. Is this normal?