IUD Periods

I've had an IUD for almost two years now. First year, no periods. Then I started to get them regularly but recently they've gotten lighter. My last one I barely needed a tampon. I just started mine and I don't even need a tampon...I've basically just decided to sacrifice a pair of panties rather than bother with a tampon. Is this normal? I would be really happy if it stopped again but I'd be a little annoyed if I was pregnant.