So Confused!!

Brianna
My period is 11 days late, I had a work schedule change so I figured my schedule caused it to be late but it still hasn't came and I am back to my regular schedule. I've had nausea, been very dizzy alot, and so tired I took 2 tests but they were negative. So what do you think could be going on and what should I do??? Would really appreciate some input on this.