You did not mention why you want to be an officer in the military or what you hope to do in the future. To oversimplify it, an officer is like saying a manager, but you did not specify if you want to manage a Walmart, Hotel or Restaurant, each one has its own set of challenges and education requirements. Your destination will determine your route there. Naval Academy is a great place, but if you don't like boats or being out at sea for extended period of time, it may not be a good choice for you. Navy used to have a BOOST program, where you enlist, go to college and then OCS, ask a recruiter if it is still available and get the details. The Congressional nomination for the Military academies is more of a formality, if the academy accepts your application, they will help you get this last step. Don't forget that all 3 Academies have a Prep School, with slightly less requirements, that may be an option for you. ROTC is an option as well, and the cost of 2 years of college, is a small price for your life time dream. There are scholarships, grants, financial aid and loans that can help make it manageable.
Your next step should be to do some soul searching and figure out why you want to go this route and what you hope to gain from it. Discuss it with a guidance counselor and find your strengths and interests. There are many ways to get there, but you need to have a destination in order to plan your journey. Good luck.