Could i be pregnant?

stopped my birth control completely about 3 weeks ago and I missed my period after having unprotected sex right after I stopped taking it. I also had unprotected sex on the day of my ovulation and a few days before and after. Now I have cramps, diarrhea, lower left back pain, and frequent urination. I tested three days ago, June 30th the 14th day of my cycle if I had gotten my period on time (which I didnt). It was negative. I have one more test and I can't get more. When should I test?