You could be pregnant, BUT I honestly do not believe it has anything to do with the test. Trust me the expensive test are no better than dollar store! Actually a LOT of women say the dollar tree tests are way better.. My sister used them with all 3 of her kids and they were never wrong, and she said she used them 3-4 days before she even expected her period.. On the other hand, remember those women on "I didnt know I was pregnant" lol sometimes a pregnancy test just will not tell you, for whatever reasons i do not know.. But your best bet would be going to a doctor. Just tell your Gyn that you are late by 10 days (which is significant) and she will do a blood test and tell you for sure. Or go to planned parenthood or something