Update -
Saw the doctor today. My scaphoid break was minor and not very tender now, so he said I can ditch the brace.
Also, his secretary (she's the one who gave me the MRI results and told me to go get the cast couture) and I weren't communicating clearly, because my ulna isn't recently broken. It was broken 14 years ago (got in a fight with a horse; horse won) and still has a little bone chip floating around.
That's the good news.
The bad news is that I have a torn TFCC - cartilage in your wrist, between where the ulna and the wrist meet. It's possible it tore some 14 years ago and wasn't a problem until it was more seriously re-injured in the accident. Or maybe it's brand new from the accident. The bone chip may or may not have contributed to the problem. Either way, it's the tear that's hurting now.
This injury won't heal on its own, and may be only slightly bothersome or very bothersome. The bone chip may or may not exacerbate things. If the pain is on the more bothersome end of the scale, then I will need surgery. Awesome.
So now we wait and see.