I agree with your T - you do need talk through these feelings. So that you don't get caught up in the emotions and possibly miss something you want to talk about, I would suggest writing down the specific things you want to talk about.
Regarding the "power dynamic", your sessions and their length have to be scheduled based on availability. Remember, this is how he makes his living.
If you feel he too freely changes the topics, you may want to ask him to bring the conversation back to what you need to finish discussing. Just say something like, "If you don't mind, I'd like to go back to what we were talking about."
Good luck.