Wait until you miss your period and then test again. You body may not being making enough HCG for the test to read. Good luck! Lots of baby dust!!!
If you got your period Aug.22 and have an approx. 28 day cycle, you would have ovulated around September 4th and your next period would be due tomorrow, September 18th. I don't think it is WAY too early to test but I would say that the cramps could be because your period is coming. You also could be having some early pregnancy cramping as you were sexually active during ovulation. If you have a regular 28 day or so cycle, test in a few more days. Good luck.
I became pregnant with in six weeks of my miscarriage in the earliest stages of my pregnancy I had minor cramping. You are testing WAY to soon since you wont get a positive until a couple days before to a couple days after your missed period. Most people could usually dont ovulate until about 14 days after the first day of their period.