Are anxiety and depression considered disabilities? If so, what is the likelihood of winning a claim, and should I have an attorney handle it?

I have a privately purchased “own occupation” disability policy with Guardian. I suffer from depression and significant anxiety. I am an employee of a financial advisory firm. My job is to perform investment management duties and manage client relationships. My depression and anxiety have caused me to be very uncomfortable in relating to clients. In meetings I often, as if paralyzed, begin shaking uncontrollably. (fortunately it’s not always apparent to others but it certainly renders me “not all there”) On phone calls I often am so overwhelmed with anxiety I am unable to clearly think and reason. I’ve grown more and more afraid to answer phone calls. I typically let phone calls go to voicemail and only reply if I absolutely must. When I speak with clients I am nervous and it shows in the tone of my voice and lack of confidence. All of this further adds to my depression and feelings of lack of self-worth. Clients have been leaving and I fear my inability to perform my role effectively will find me jobless before long. I fret at what I would do as an encore career because I don’t feel qualified to do anything. I am looking for guidance as to whether my situation would be considered a disability that could be claimed? If so, am I best having an attorney handle the initial claim and what’s the likelihood of winning a depression/anxiety claim?