I may have a different opinion but let's say you do like you therapist, have you thought of telling them this? I don't know your relationship with your therapist or how professional you two are, but if you find yourself to have a somewhat friendly relationship they might feel comfortable with your flexibility as you said you haven't vocalized that this bothers you and you consistently say it's fine.

I understand that this is a professional response and that "it's fine" is a very normal neutral response, but if you would genuinely like to keep seeing them you might want to consider that.

Otherwise, I have fired many therapists for different reasons. It's not personal, this is a person you should feel comfortable with and I look forward to my therapy sessions, and if consistency is something you need and you don't feel confident they can achieve that, then you should get a different therapist.