I assume she may be receiving speech therapy services (and you mentioned OT services); ask your therapists how to approach the teachers/coaches.
By the way, my daughter was an early talker, but when she went to 3 year old preschool she was initially quiet/observant, and I actually had a mom ask me if she could talk. There is more "action" than verbal interaction in preschool. And it sounds like you are putting your daughter in classes/activities rather than preschool; so unless I am mistaken you may be right there.
By the way, I am a speech pathologist who does work with birth to three years. If you are going to be there with her, unlike preschool, you will be the one assisting her to the bathroom. Share what is necessary with the coach/instructor, but there may be no need to go into detail unless a particular situation presents itself.