It all depends on when you implant. If you didn't implant until 9 or 10 dpo, then it's too early for ANY test to detect the pregnancy. Some women implant even later than that! That being said, my experience with $ store tests is that they are pretty sensitive. During one of my pregnancies, they detected hcg just as early as the FRER.
They can be bad about evaps, though, so your best bet is to toss it after the time limit.
Try not to stress. It's still early. One of the girls here didn't get her BFP until the AFTERNOON of 11 dpo and she was testing the whole time. So you are totally still in the game.