Still a chance?

Im eleven to thirteen days pod and I've been cramping since Sunday. I've taken tests and keep getting bfns. I've been peeing a lot but I usually do before af who is due tomorrow through Monday sometime. My cervix is high though and I've had a lot of creamy cm lately but today it seemed a little more clumpy. My breasts don't hurt but do seem swollen, sometimes they hurt before af, sometimes not. Am I out because I had a bfn this morning? Also, I've had headaches (and at one point a migraine) recently which isn't usual for me so could these be another symptom?