I don't know if I'm pregnant.

Hello there everyone. I was just wondering how I could tell if I am pregnant. My last period was July 4th and I had relations with my fiancé from the 10th-21st. I took a test Wednesday because I thought I would get my period August 1st but it was negative. And now it's the 9th and I still haven't gotten a visit from aunt flow. I wanna take another test but am pretty nervous. What if I'm not pregnant and I'm going crazy?! Also my breasts are sore and I have crazy diarreah... But that's probably more in my mind than anything else....