Could this be it?! (Kind of long...)

Hello ladies... I have attached a picture of this month showing my fertile window, when we bd'd, and when af is supposed to start.... I rarely have any pms symptoms before af starts, and if i do its very mild.. But...The past several days i havent been feeling myself, and overall feeling bad. I have noticed in the past 3 days some very light cramping in my stomach and just a churning kind of feeling.. And been nauseous on and off. I havent thrown up, but came very close. I tried to smoke a cigarette and had to put it out because i gagged with every inhale. My appetite is a little different as im just nothing sounds good... And in the past 2 days my boobs are becoming more and more sore and sensitive. I took a test afternoon of 2/13 and 2/14 both of which were negative... But my emotions have been all over the place and uncontrollable. I have been pregnant twice before each of which early on i started burping all the time like crazy, which has also started happening in the past few days.... All of this makes me think i am pregnant... But the tests were negative. Did i just test to early? Or could this be something else? Any insight ladies? Thanks in advance:)