Ok.

Have you tried different brands of tests? Some are more sensitive than others.

Condoms are only 97% effective at preventing a pregnancy, so if you are using them there is still a chance it can happen.

As for the Dr, you don't need parents permission once you are 16 & they cannot tell your parents anything that happens during the appointment. I think you really need to get to one somehow, because an absence of periods isn't normal usually, there could be something going on, even if it's not pregnancy.