I do recommend an evaluation by a dr. that can basically say what you already mentioned. "I was treated for depression in a hospital in 2000. I checked myself in. It's rediculous. I was seeing a doctor and it was a medication side affect." That in effect will be your lawyer! You can mention you had a permit from ? to ? with no incidence at all. No need for a "2nd Amendment lawyer." You are not going in there to argue law. If we were a "shall issue" state then yes, because your denial would be based on the law and to be honest NOT the 2nd amendment anyway. "May issue" is a more subjective term for you in this case and requires a different defense. You have to impress the judge that you possess good moral character, and the Dr helps to establish that. Consider having letters from people you know that are somewhat respected like Police, Employer, Judge...
BTW sometimes even in a "may issue" state the defense can be a matter of law, I just do not see it in your particular situation.