CD40 24dpo negative tests still no AF

*sigh* I'm in a limbo AF still hasn't come and I'm getting bad lower back pains and terrible headaches. I was also very light headed yesterday and I feel like my food won't go down my throat.

All the hpt I have taken are negative. And they are all FRERs. I have driven myself a bit nuts reading posts of people who have had pregnancies without ever getting positive hpts or positive blood tests.

Should I just assume I'm not pregnant? Should I wait for another missed period and then fuss for an ultrasound?