I think you need to read it in a blunt manner, so I apologize for being blunt, but here goes....
DON'T JOIN NROTC IF YOU ONLY WANT TO BE A SEAL.
NROTC does not exist to make SEALS, SWO's RIO's, etc. They exist to make OFFICERS.
ROTC is 4 yrs of time and dedication, unless you are psychic you cannot predict what will occur in the next 4 yrs. You can't predict if you are playing ultimate frisbee and dislocate your knee which may require surgery and jeopardize your chances. What you can predict is that if DODMERB clears you after that surgery for a desk and not SEALS, your butt will be sitting at a desk for 5 yrs.
It is great to have that dream, and by all means go for it, just be prepared to accept the fact that for some dreams are just that dreams, they never become reality.
Let's also play the game, you get selected for SEALs, go to training and you wash out. Guess what, you still will owe the Navy time. This is also a reality for many people who have walked the path before you. Just saying, be ready to take whatever is handed to you, good or bad.
In other words, DON'T DO NROTC JUST TO BE A SEAL, DO IT BECAUSE YOU WANT TO SERVE AS AN OFFICER IN THE U.S. NAVY.
Want to know what they call a Navy Ens. SEAL? Ensign!