Oh how frustrating - things seem to fly by during visits, we forget what we meant to ask, or maybe the doctor uses jargon.
Have you considered bringing an extra person along, who has the checklist of your questions, and can record what the doc says? Or maybe record the visit on your phone so you can refer to it later?
Also, if there is a "patient portal" usually you can ask questions or get clarifications within a few days of your visit without having/paying for another visit.
Sue