A woman that I work with tested negative with both urine and blood tests for both of her pregnancies.
With her second pregnancy,
she had an appointment for an ultrasound because her doctor thought that she had a tumor on her uterus,
which was why he thought she was getting bigger,
but it ended up being a pregnancy!
She was at 3 and a half months at the time.
I am two weeks late right now,
and both my at home tests were negative a week and a half ago,
yet I`m starting to get a bit bigger under the belly button and am occasionally nauseous.
It`s not the best thing when a woman cannot get a positive test when they are really pregnant,
but I hope that`s what`s happening with me in my case.