As an Air Force wife of 20 years, I too went through the military process to try and get a diagnosis. Hind sight being 20/20 ....... I had numerous symptoms and would call to make an appointment only to get a different doctor each time. Consistency is key here.
Hopefully the health system keeps you with a Neurologist.
I had military friends who were diagnosed with M.S. using the military health system.......the hard part is getting all the criteria for a diagnosis to hit at the same time. Your doc my suspect M.S., so that is the path he/she is trying to take to get a diagnosis. There are only so many things they can test. Evoked Potentials would tell if you are failing some key things that you may not really even notice! These tests can be helpful, but only certain positive tests can give a confirmed diagnosis.....one of those being a positive MRI consistent with M.S. The others are: symptoms that reoccur over different time frames.
Disc problems can cause some real havoc. I had some issues I blamed on MS for years that were actually coming from cervical neck issues.

Bottom line....don't get freaked out. Many things mimic M.S. If you are 45 you must be at the tale end of your enlistment? If so, think about life insurance etc BEFORE there are any diagnosis made such as M.S. Are you close enough to retire or would they put you into disability retirement? Insurers won't want you with a chronic disease. Thats just something to think about.
For 12 years (during the military years) I had a clean MRI so no diagnosis. Symptoms came and went and a couple distressing ones stuck around....Boo.
I think the Military Docs tried, but all the ducks were just not in a row yet. And with that in mind we all have to wait. No one ever told me that I "may have M.S." However; after getting my military records for a civilian to review, they had made notes about a suspicion. I guess I'm glad they never mentioned it so I would not worry. The other side of the coin is....there is a relief when a diagnosis is made so that you can confirm your sanity!
Note: I was diagnosed in 2002 and I still do most things and have slowed down on somethings I probably would have slowed on anyway due to age (53). I take the meds and my disease is stable. Your anxiety is normal at this stage of the game and we have all traveled that road. (Once for a week I locked myself in the bathroom for a couple hours and took a jet bath and cried my eyes out). That was before I knew for sure and not knowing is worse.

I won't ramble on anymore.....peace be with you and hey; THANK YOU FOR YOUR SERVICE!