Here is the relevant part of her reply message, she thought it was definitely a valid question and she agreed with my observation that I'd probably not want as much session time in the future:

"Good morning, Leah, that is not a thoughtless question at all. I would absolutely work something out with you that you could afford. But I truly believe that as your therapy progresses, you will be needing only one session a week."

I imagine she's right about needing less time in therapy: a lot of my issues are circumstantial right now, and are likely to ease in a year, I have already worked through a fair amount of the PTSD-related stuff. Hopefully I'll still be able to direct frequency, as she's let me do so far.