Pregnancy test are all pretty much the same, except that some are a little bit more sensitive to the HCG hormone which is produced when you conceive. Now, most of the time, it will show up as early as 3-4 days before you start your period, but for some woman, they start producing HCG late, so it won't show up on the test. Some of the symptoms that you are having could be that your body is trying to start it's period but, I would try to take a test until the 22nd of this month and if it still doesn't show up, then I would go to the doctors so they can do a blood test, which will absolutely tell you if you are or not. Good luck!