Im so confused... Still dont understand periods at 21.

Ashley • Ashley • Taken by Coby ♡ • Emily Marie and Lexus Rae

Been off birth control 2 months, had one period and now im 9 days late on my current one. I took a test, it was negative. But i am never late when on or off birth control. I am not sure what is going on, or maybe the test cant read yet? Idk.... :(