Sometimes your body does not produce enough of the hormones necessary in early pregnancy to show a possitive urine test. This is rare, but it does happen. Go to your doctor and have a blood test done. They are much more accurate. This happened to me with my second child. I missed 3 periods before the test showed possitive (including the 1 at the clinic)
Just last month my cousin completely skipped a period. She wasn't pg, but thought she was, and the tests were all wrong.
It turned out that being very stressed about ttc and work made her completely skip one. It happens. She started exactly 8 weeks after her last period.
Don't worry, you're probably not pg. Call your doc if you need further reassurance.
Anything can cause ur period to be late.. Everyone isnt regular all the time.. Calm down. If all the tests are showing negative you can go to the doc & they can give you something to jump start your period. Hope that helps
don't stress yourself
you know some times we can have these problems when you are under stress (work, study,...)
bye