17 years old, could i be pregnant?

you could have gotten a negative test if you tested during the day and not your morning pee. You need to test again in the morning, or hold your pee for a while to test again to be sure. The other thing could be that you are going to miscarriage. A positive test is a positive test, but some women mistake a evaporation line as a positive result. JUst test again in the morning to be sure.