Jane, please try to relax a bit...I know, way easier said than done ATM, but there is the possibility you're stressing yourself into believing you are pregnant.

Try taking the test again in a bit as recommended by the box. Until then, please try to remain calm...I know I'm advising something difficult there, but Hamster is correct. The more you connect mentally what could be happenstance symptoms to pregnancy, the more solidified the thought process is going to be.

In my prayers, and hoping nothing but the best for you,
Harley