I am not trying to conceive and have a mirena coil, so chances of pregnancy very slim. But I've had regular periods since having the coil for over a year, and I'm currently 4/5 days late and have very unusual exhaustion. I had a cheapie test in that is a year old that I took today and it is negative but I'm still paranoid. Reviews for the test say it isn't very sensitive and only 25 miu and false negatives likely, would this still be the case this late?