PLEASE HELP

So, I've been having incredibly bad dizzy spells, & all of the symptoms that my period is coming soon, like back pain, breast tenderness, etc..., however, my period was due to start almost 2 days ago and still hasn't yet! I took two pregnancy tests, one was 6 days before my period was due & the other was 4 days before. They both came out as a BFN. Should I take another one? Is it possible I might be pregnant??