Academics: VERY solid! Nice that your GPA and class rigor confirm. Agree you should attempt earlier ACT/SAT if possible PLUS taking the writing/essay, even if you think you'll never need it (USMA - verify). Depending on world events, you cannot assume things will get "better" for seats at exams, and the new landscape is this: when you get a seat, that may be the only time you get to take it - so you MUST deliver and score well! Gone are the days you can take willy-nilly up to the deadline! Try to take AP exams, and hit validating scores (in core curriculum).
Sports: Tennis. NICE you are doing this 4 years, state qualifier, and on track to be captain.
ECs: NICE you are already doing, and each line you cite future goals. Just a tad laundry-list-ish, but again, I understand you are just listing them here. Make sure you have good answers to what on your resume is the most meaningful and why (type of question).
Don't overthink acceptance to Summer Seminar. Apply to all SA summer programs - SLE, USCGA AIM, NASS, and Boys State - you have no idea where you will get in, which will be in person, virtual, or cancelled.
And since you seem to be working ahead:
If possible, get anchoring/final scores for SAT/ACT as soon as possible, and CFA, and DoDMERB done during the summer before senior year starts. This means working backwards for your CFA training and testing window, and also strategically hitting enough elements through one SA application to get DoDMERB triggered.
Agree no reason to contact congressional staff at this time, and keep in mind this is right in the current cycle's nomination season.