I'd love others opinions

Hi. This is my first 'topic' so not sure what to write.
Basically I should have been on my period 12th of this month. 
I'm not and so far iv taken 3 pregnancy tests, they all say negative. 
I know I should go to the doctors but before I do I want to make sure I really need to.
My question is has this happened to you, what was the outcome? 
Surly 2 weeks late should show on a pregnancy test.