Sorry, a little bit of a late reply, though.
I am on SSDI and it has the same as SSI that you can voulenteer as long as you are not getting paid cash money or paycheck.
I too have a goal to someday voulenteer at something when I feel I would be able to commit and show up when I was to be there.
How did it go with the appointment? If you don't voulenteer there there are alot of other places that take voulenteers. Best of luck to you-Chris
______________

~KRIS~
If you think you have totally gave up, you haven't, because you are here!