Scarlet, I'm extremely proud of you for doing this -- the whole thing is a major accomplishment for someone with agoraphobia and past unpleasant experiences at the county. Well done.
Even if this DBT class is not up to snuff, the fact that you're going is a major achievement and that's a Big Deal. You're smart enough to study the workbooks and begin to understand and use the concepts on your own. But it takes actually getting out there and doing the things we dread if we want to confront our phobias and start getting beyond them. Can't do that staying within our comfort zones.
None of this is anything you wanted to do. It's all part of reaching your larger goal. Give yourself a pat on the back and never mind the nurse or the extra labels. You did it! You faced it! Good work!