Your military "general" practitioner is way off base with his assumptions.

Your military ENT doc is off base also if he stopped with an audiogram.

You suffered a TBI/Concussion, Blast Injury. Much is called for in follow-up to evaluate your Concussion injury/TBI injuries; as well as your Blast Injuries.

Give some of these studies a read, especially relating to the audiology, ear injury aspects of TBI/Blast Injury, and Audiology Evaluations; copy them and show them to a specific Neuro-ENT M.D. (ask for that referral thru the VA/Military system).

Auditory and vestibular dysfunction associated with blast-related
traumatic brain injury

Tinnitus Evaluation and Management Considerations for Persons with Mild Traumatic Brain Injury

Current Perspectives on Traumatic Brain Injury

I hope this gives you some insight and information that is useful in your road to recovery.

Best Wishes >>> Thanks for your service. <<<