It's hard to get everything communicated in 15 or 20 minutes, but if you do a little preperation it can at least help. Try listing out what symptoms you are experiencing that are bothering you that are most important, or if there are meds that are giving you problems, the biggest problems you are having.

Put the important things on note cards and bring them in.
Also write down anything that you think is vital information for them to know. [like oh, hey, I felt manic for about four days last week and slept about an hour each night]

Anyway, notecards might be helpful with specific points to share.
I do it every once in a while when I can manage it.