If you don't get an appointment to the USNA, I recommend trying a college with NROTC. IF you don't get a scholarship, there's always the college program and advanced standing. You can get a commission, and if you want it badly enough, you'll get it and pay your own way if you have to.
Going enlisted if you really want to be an officer can become a painful experience. Unless you're willing to be enlisted for four years to an entire career, go officer any way you can!
Good luck!