To add to this...
To be found unfitting for PTSD, you must present evidence with the ABCMR that your condition did not meet retention standards per AR 40-501. Chapter 3–33.
Anxiety, somatoform, or dissociative disorders
The causes for referral to an MEB are as follows:
a. Persistence or recurrence of symptoms sufficient to require extended or recurrent hospitalization; or
b. Persistence or recurrence of symptoms necessitating limitations of duty or duty in protected environment; or
c. Persistence or recurrence of symptoms resulting in interference with effective military performance.
That is not to say that the Army did not get your MEB incorrect, so hopefully your packet is able to demonstrate that you indeed did not meet the standards for retention. Simply having PTSD does not make you unfit. There are plenty of soldiers that have PTSD and are able to thrive on active duty.
Out of curiosity, why did you not apply to the PDBR?
https://health.mil/pdbr