What the hell!@#$#

I was ment to start my period on the 30th of march. It still hasnt come. Iv took loads of tests all negitive . Im 8 days late. I have never been this late before. I was feeling really ill and sicky today and even was sick i feel drained and could easyly sit and cry. Im so fustrated! Why cant i just get a positive test or start my period!. Anyone else experianced this???