of course those symptoms can also be signs of impending period, and a period can be late due to stress.
All you can do is try and relax and tests every few days until you either get a positive result or your period.
A test will only show positive once there is sufficient pregnancy hormone within your body, which is why some tests calaim to be able to detect SOME pregnancies up to 5 days before a period is due. It all depends on when you conceived and how quickly the hormone increased.
Test with the first wee of day for more concentrated urine.