, congrats with the LOA. It appears you are on your way to a full Appointment in January, subject to Nomination, successful graduation with good conduct until Reception Day at WP.
Regarding your career aspiration, it is nice to plan ahead. In fact, planning 10 years ahead from today is quite realistic since that's when your service obligation ends after serving 5 years in the Army and be on IRR for 3 more years. Nevertheless, many things can go differently during your time at West Point or at a AROTC program. Deviation from this plan is most often caused by you, and secondly by the needs of the Army.
If contemplating MI, you will have to most likely branch detail with combat arms branch like the Infantry, Armor or Field Artillery. You can get MI if you are ranked in top 50% at the Academy. You will start doing MI work after you make 1LT and do some time as XO to Company CDR. So you will not be doing MI work straight out of commission. In fact, most successful MI officers do combat time or serve in combat tours during their careers. Some of my close friends did just that while serving in MI. One MI is still in who is G2 representing the US at NATO. And one is leaving as O-8 next year. Both WP grads.
Getting nominated as a Rhodes Scholar to study at Oxford then serve 5 years then go to law school have been done in the past. But not often. Perhaps one cadet every 5 years. All this sounds great but set your eyes first on the BCT next summer, then being prepared to do well in your Plebe AC year, then summer training, etc. Keeping your grades up and maintaining top order of merits are not always in your control. They are impacted by others as well such as military responsibilities at WP, Athletics (intramural/Varsity), ACFT, leadership responsibilities, opinions of those who serve with you and senior officers in your COC. Be sure to be a good fella to others and not be that loaner who is focused on his/her goals throughout the Academy life. You will also have to remain healthy and medically fit to serve before commissioning when you're a Firstie.
Be sure to become a good analytical writer. Your ACT English and SAT Verbal, AP English Comp and Lit are good indications to how well you may perform in college reading and writing classes. English writing classes at WP can be challenging. Since you want to become a lawyer, you can do this two ways. You can go to law school after leaving the Army or you can go to law school during Army on Army dime by joining the Army JAG Corp. You can do this as early as after serving 2 years and do lat transfer to JAG. The JAG Corp will want to see that you have taken your LSAT during your Junior or Senior year in school and have a guranteed admissions to law school as early as at the end of your Junior year or before applying to the JAG Corp. I have been told it is easier to take this route if graduating from a AROTC program rather than from West Point or Service Academy.
For this reason, my daughter made her decision to go NROTC rather than to attend a Service Academy, although she considered Annapolis and Air Force as options. Air Force has the largest JAG, then Army, then Navy. Well it was one of her reasons. It is easier to lat transfer into JAG between years 2-4 while meeting and exceeding your performance at your current job. Also your CO has to release you in order to lat transfer.
Bottomline, you can plan all you want but the outcome remains to be seen subject to the needs of the Army, your performance, your continuing interest, and your acceptance to programs that are most competitive and sought after by many aspiring MIDNs, Cadets, and Students around the world. So for now, focus on finishing strong in your remaining two semesters in high school and don't forget to enjoy being a kid one last time before leaving the comforts of your family!