late period with Coper Iud

Did anyone notice their cycles change when the got the IUD .. I was on Oral birth control for years and never worried ... right now my IUD is more of a nightmare then a help :(   I got the 10 year copper IUD in October ... it slipped out of place and I had the new one put in just before Christmas.. it's a 5 year coper IUD ... periods are heavier and longer.. and now his month .. I am late ... today I did a pregnancy test and it was negative... just really worried. I am on medication that will seriously damage a baby so getting pregnant is NOT an option for me