Hi viola,
We try to keep track in writing of the things that we want to be sure to mention to the T. We used to do it in a journal to him that we brought to the office, and now we do it in an email that we send the evening before our appointment. Sometimes we start the email a few days earlier if there's something we're worried we'll forget, and then we save it in drafts and add on to it until the night before the appointment.
Then even if we decide at the appointment that we don't want to talk about that thing, at least we'll have the option. Otherwise, important things can get lost if whoever goes to the appointment doesn't remember them or is afraid to mention them, etc.