Negative pregnancy test late 8 days

Marketa

Hi i wanted to ask i normaly have regular period each month this month i am 8 days late but the pregnancy test says i am not pregnant i have tried clear blue digical and also pink dye ones i have never experienced this before i went to see doctor yesterday she didn't say much about it she said i may be pregnant but my hct levels are not much high tahts why the test doesn't catch it