Could I still be pregnant

Yesterday I went to the doctor they gave me a blood test it was negative, I also did several HPT they were all negative. On September 25th was the last day of my period ,  September 26th I had unprotected sex October 19th the day I was suppose to start my period  I had discharge with blood like implantation bleeding for a day, the next day I only had discharge for a day no odor I'm not stressed and I've never missed a period a day in my life. I'm 6 days late now should I retest again? Or is it possibly I'm not pregnant lately I've been vomiting and still have mild cramps, but no period and several headaches also fatigue. I also having the feeling with the mild cramps that my uterus is pulling and I have mild back pain and no I'm not stressed.