I'm 16 DPO 2 days late on my period. I had a two day headache a week ago. Been exhausted all week long. Like OVERLY tired at work. I'm a teacher. I have been having come and go tiny cramps for two days. They're starting to go away. Massive nausea in the morning about the time i get to work that comes in waves one or twice then goes away. I took a test today. Cheap dollar store test. It was negative. Could i still be pregnant?