Late period with IUD??

I have the copper IUD and my periods are usually really regular, 28 days like clockwork. However, this month my period was supposed to arrive 2 days ago and it hasnt. I did take 2 combined contraceptive pills about a week ago because I was trying to delay my period (I realised this wasnt going to work and stopped taking them), however now I'm concerned that I've messed something up. Any help?