I am on long-term disability for my anxiety. I am fortunate that I have two trusted professionals who know me really well and were able to give details to SSI about why my anxiety is so disabling. When I applied for disability, I was approved on the first try...but on average, people usually need to apply more than once before they finally get approved. So if you do apply, don't get discouraged if you don't get it on the first or even second try. It will definitely benefit you if you see a doctor and/or therapist who can increase your chances of getting disability.
I do not work, but I am allowed to work part-time and still receive benefits. SSI will give you a certain amount of money based on the number of hours you work. Also, if you decide you want to work full-time, SSI will help you transition from not working, to working part-time, to working full-time...they will slowly decrease your benefits until they feel you do not need their help anymore.
Oh, and if you don't earn disability the first time you apply for it...I would recommend getting a lawyer.
Hope this helps