Home pregnancy test, though not 100% correct is usually about 95% correct at least. I suggest, go to the store and get another one, read the instruction more carefully and do it again, just to make sure - text today doesn't need the first urine in the morning, but I still suggest you try it with the first urine, to help accuracy.
If you have done the test according to all the instructions and you are still negative, then most chances is that you are not pregnant. You haven't stated at which age did you start getting your period, and if it's usually regular. There is a good chance that also, your stress is effecting your body and this is why you are late. So I say, if the test come negative wait another week or two.
For more information about options if you are, check out:
http://www.plannedparenthood.org/