Is Pregnancy Possible Despite Negative Pregnancy Test Results?

My last period was Nov.24. I had unprotected sex Dec 2nd (he did not cum in me). Ever since i've had cramps on and off. I recall a few days after having brown discharge when i wiped. And two times finding what i feel to be dried blood in my under garments.My period was due The week of Christmas(no period). I had unprotected sex dec.28th. It is now Jan.7th and still no period. I took a test last night and it was negative. Can I still be pregnant?