For the OP . . . first, thanks for being honest re why you took geometry. That said, it creates a bit of a challenge. USNA knows the highest level of math your school offers and generally expects students to take (and excel) at that level. Here, you helped your GPA -- which is good -- but now are in a bit of a pickle b/c what USNA doesn't want to see is folks taking easy courses to get good grades when they should be challenging themselves.
Let me be clear . . . I'm not criticizing you and fully understand why you did what you did. It makes sense and probably is a net plus for every school other than a SA. Plus, you have a very strong core foundation in math from which to build rather than struggling throughout your h.s. years.
So what to do now? At a minimum, take pre-calc at the honors/AP level if it's offered. That way you are at least taking the highest level you personally can take and that's probably the best approach. Second, you say your school doesn't accept outside credits -- does that include college credits? For example, what if you took pre-calc at a community college over the summer? It seems stupid for your h.s. to force you to repeat material you already took at a college level. Then again, I don't pretend to understand our nation's public school system.
Also, be sure you're taking the highest level of other courses (chem, physics, English, history) that you can handle -- honors/AP/IB if at all possible.