The only thing you can do is take another test. If there is a $ tree around you, go in and grab a handful of theirs (they are only $1 and are sometimes able to detect pregnancy before other "leading" brands days sooner). Just remember that not all dollar store tests are the same... going to a place like Family dollar or dollar general is not the same, and their tests are actually less sensitive to hcG amounts present early in pregnancy.
Good luck, and test away until your period shows. If you still haven't received your period by the end of the month, schedule a doctors appointment and have a blood test done. They are more accurate.
Good luck!