i first tried with my school counselor when i was 16. she asked me a few questions directly (after she knew me a while) and i panicked and said "no" (e.g., are you self harming + stuff like that). when i eventually did feel comfortable i wrote her a letter.

i wonder if maybe writing out what you want help with might be a good idea, and then you could give it to your dr in the appointment if the words get too much to say themselves?