Your chances are slim to none on getting RTD with MS. If you believe the VA rating matches up with your symptoms I would accept the findings. I know that may be hard to hear since you want to stay in but that's your reality. If you believe that the VA messed up and your symptoms warrant a higher rating then what
@chaplaincharlie said is correct. Request a VARR and try to get the rating increased because the DOD will mirror that rating for your PDRL medical retirement leaving you with a higher monthly compensation amount. Most that fight for a fit finding end up with the worst result as they minimize their symptoms to medical personnel to try to show that they can still serve. The problem is that there are certain conditions that will have a very high chance of being found unfit regardless of the symptoms.
If you are close to hitting your 20 years of AFS after you are found unfit you can apply for COAD. That is where they let you stay in and accommodate your disability and you continue to work until you can retire at 20 years. You need to have at least 15 years of AD time in to qualify to submit a COAD packet.