Applying for SSI/SSDI (from a complete newbie perspective)

Forgive me for asking what are likely well worn questions, but recently while talking with an employment specialist at my mental health support clinic, they indicated that I might be eligible to get SSI/SSDI - this took me by surprise, as I'd always heard that it was really hard to get, especially for non-physical disorders.

I have MDD, disthymia and pretty bad anxiety (some of which relates to past bullying in the workplace). Over the last 5/6 years, I've also developed balance issues, which don't typically stop me from activities completely, but make them much harder, as I consciously have to monitor & correct my balance when standing or walking.

The question that seems to leap out, is to what degree the above affects your ability to function at work (presumably any kind of available work). But what's entailed by the definition of severe in this context? Total inability, or is there some kind of scale of partial inability?

I hope you are approved when you apply. It probably is true@hard to get for non-physical disorders. I am on SSI for panic disorder/agoraphobia, depression. Got approved the 2nd try with a disability advocate appearing before the judge on my behalf. I have 2 friends on SSI also for mental disorders, one for bipolar. If my memory is correct there are some people on for MDD. Yes there's a scale of partial inability of some kind. If you are able to work to a certain degree, your SSI amount will be less.

I applied with a mental health disorder approved on my own first try. But I hear voices and when that's going on I'm totally unable to work. Not that I can't but no one wants me around them.