... What should I work on?
Clearly you have academic talent and high performance -that's impressive. Also really liked the leader positions noted.
For the academies do your due diligence research on what helps you stand out - not my area of focus since my DS didn't want it, but boy's state, eagle scout, NHS, captain of a varsity team, any distinctions athletically. Could you compete for them at the NCAA college level at something? Or can your folks pay 300k to photoshop you as a standout rower for USC? (just kidding). All well documented and you should get a good sense of how competitive you are. Also, talk to their admissions team. Annapolis heavily recruited my DS and they were very informative/ honest / pretty great to deal with. I felt he knew exactly where he stood with them and what he needed to do if that was his path.
On your impacts - I recommend you articulate further - Where did you stand-out as a scholar, athlete, leader? I'll be honest, I recommend changing your verbiage from "involved" to describe participation in a club - alternatives like "lead" would be more attention grabbing as where you lead - were an officer / leader. The number of hours of comm service should be noted - that's good , but---what did you do? What impact did your service have and did you have on the project(s)? Show how in the classroom, on the athletic pitch, in organizations, you have been a leader and use your essays to show how were you effective and to tell them who you are. Can you be a captain of your swim team next year? Can you itemize how many AP/ honors courses on your app? National honor society? Also, what makes you unique? Have you lived abroad? Did you take the ACT also, and how did you do? With such a strong showing on the SAT you might max out on some of the ACT scores/ composite score - why not try?
Obviously you're in the top 2% of SAT scores, great GPA. I think for ROTC if you can articulate what makes you stand out you are very competitive. recommend applying to at least 3 branches (Army, Navy, USAF, Merchant Marine, Coast Guard) and to both ROTC and Academies if that is your interest, and see what happens b/c a lot of young people and their family/ support teams on this board were also very talented and got TWEs thin white envelopes/ ding letters - for the academies and some ROTC programs. many were definitely strong in a lot of areas - again talk to their recruiters. Also talk with the coaches - The track coach from West Point was excellent in advising my DS you would need a ____ time in ____ events. Swim coaches can do the same. Good for you to know where you stand.
Hope this helps / good luck!