Possibly Pregnant?!

For the past 3 weeks or so I've felt pregnant. I've felt extremely nauseous, when I never am, I've had to pee slightly more frequently, I'm getting headaches every night and getting much more tired, etc. this would be my second child. During this time I have felt pregnant, as I did with my first pregnancy, I just had this "feeling". But I keep getting getting BFNs... AF is due in 6 days, but I've been feeling like this for 3 weeks and my last period was extremely different from my typical period. my question is, could I still be pregnant??