Never hurts to give Admissions a call. They very well could be fluid with that 8 JAN deadline. Since you did your part, they might understand that that you are simply waiting on the fine Americans at DoDMERB to evaluate your AMIs and make a final determination. I am speculating, but I doubt there is a flag on any record at DoDMERB regarding LOAs. DoDMERB reviews thousands of records and is strictly there to determine medical suitability for commissioning. LOAs are admissions functions. They are more there to "carrot and stick" applicants they especially like since those applicants are most likely applying to other good schools. However, waiver adjudications are made by the commissioning source (i.e. USNA). This is where you might probably get flagged an an LOA candidate.
Again, Admissions can give you the honest answers. Even if they won't extend the deadline, they can probably provide a way forward for your appointment. They obviously want you to come, they are probably willing to work with you to make that a reality.
