Nonhoromal copper IUD missed period?

Anyone have this happen to them? I got the iud placed last week when I suppose to start my period but never did... It's probably almost a week late now. Negative pregnancy test. The doctor told me I shouldn't have missed my period because I have the copper IUD and to take another pregnancy test in a week if it doesn't come...

My period has only been late once! When I was pregnant. Which I don't think I am because of how late I am I would of got a positive by now.

Once again this is the paraguard, copper IUD, with no hormones. The mirena or hormonal one I know can stop your period but this ones not suppose to.