Thanks for the chance to help. I am an attorney with over 12 years military law
The criteria for a Medical Board is if the underlying condition was caused by the military.
1. A soldier
injures his arm in training and it will not heal properly. THat is a classic case for a medical board since the injury was caused by training
2. A soldier enlists and after enlistment they find that the soldier has an anxiety disorder that was not caused by the military. Such a case would not be a case that should go to a medical board, since the condition was not caused by the military.
What you describe does not sound like it is the basis for a medical board. Unless it is clear that the anxiety disorder was caused by service (for example, a soldier who develops PTSD due to combat), the military should not send the soldier to a med board.
If you feel that your condition was caused by the military, you would want to present medical evidence to support. For example, have your doctor write a letter stating as much. This could be grounds to change the chapter to a med board. But short of medical evidence to support such a change, you are not going to be able to stop the chapter.
All that said, if there is evidence that the service aggravated your condition, or even caused it? You can apply to the Veterans Administration