I'm late

heather
I have a 10month old and at my 6 week pp check up I got the skyla iud. Everything has been fine since. Normal and regular periods since. Well as of today I am 8 days late. The only time I've ever been this late is when I was pregnant. I've taken 3 tests all of which are negative. Has this happened to anyone before? I've heard the skyla could slow your bleeding until it eventually stops but I've had normal / heavy periods since the iud was placed and now nothing. I'm so confused!