negative test positive signs?

Courtney
Hello ladies, 
I have been ttc for 6 months now, my period is always on time, 28 day cycle. 
Anyways I am now 9 days late but I took a clear blue test 2 days ago and it was negative. I'm breaking out like crazy, super emotional, nauseas after eating and super tired. 
Has anyone had a negative test even with a 7 day late period? 
I'm hoping I could still be pregnant but if not then why is my period so late?