The link gokings posted was started by me; my DD had her sights on USNA since she was around 13yrs, and planned to enlist and reapply if not accepted. The feedback on that thread changed her course for backup plans.
One important thing we discovered along the way is that you will never become an officer without a college degree.
For DD, the first question was, did she want to be an officer or did she want to just be in the Navy? Her answer was officer.
The next question was how to get there (officer) if not offered an appointment to USNA as a hs senior? The options were either a prep school (such as Greystone), a civilian college (State U), or a SMC.
State U was not an option she liked at all, so that was off the table. So it was prep school or SMC. Prep school is a good option, even as a self prep; Greystone in particular was appealing to DD, with a laser focus on getting into a SA. However, if she went to Greystone and was not offered USNA the following year, then she was back to square one.
For DD she decided on a SMC, and she has already been offered an appointment to VMI. (Still waiting to hear from Citadel).
She's determined that she will not reapply to USNA if she isn't offered an appointment, because her end goal - become an officer in the Navy - can become reality in 4 years through either VMI or Citadel. In your case, the same is true from A & M.
At a SMC you will be going through a tough freshman year, similar to Plebe year, and if you reapply to SA you'd basically "lose" that year and do it all over again at a SA. None of your credits will transfer, although you could probably validate out of many classes. So that would be two pretty rough freshman/Plebe years, and it would take five years to become an officer instead of four years.
For my DD, she has decided to throw herself into a SMC and give it everything she has, without the added stress or distraction of reapplying to USNA.
I'd suggest figuring out your end goal, where you want to be and what you'd like to be doing in 10 years, and decide what the best way is to get there for you. I wish you all the best!