A lot of people are saying once a week is not enough.. I guess it could be true for some people but not for all. We all learn a bit different..
I am in NO WAY trying to sound cocky at all, but I flew once a week, sometimes I wouldn't be able to fly for two weeks.. I got my student certificate at 6.2hrs and I got my PPL at 42.2 hours, for a total of just shy of 6 months.
When I left the airport I didnt just pack up my flight bag and put it away until the next lesson.. I would bring my study material to work, gym (during cardio) and literally anywhere I went. I would study the books I got (Jeppesen) and online material EVERYDAY, I have Flight Simulator X with the Alabeo DA40 (my training airplane) with Yoke, throttle quadrant and some rudder pedals and to this day I use it every single day.
Dont just study during the 30 minute ground portion of your lesson, study ALL THE TIME!
I couldnt afford to fly much more than I did, so I was almost forced to try to get my PPL as close to 40hrs as possible.
I think you should find another CFI, if youre here asking what you should do, I dont think your CFI is fully doing their job. He should tell you what to practice, where your strong points and weak points are, you should have a better overall picture of where you stand, and how much longer you have left, but from your description, sounds like your CFI just wants your money. I could be wrong.
-MDA40