Quince
We have had posts a little like this before. If you have a concern then TALK! dont bottle it up but have a chat with the CFI explain you have a lot of hours (36) and why are you not solo yet? Also explain that you are getting demoralised!!!
There are many reasons which may not be to do with your piloting skills or lack of them!
Usually weather related.
Even if the instructors are not happy to sign you off solo with 36 hours you should expect to know WHY!!! identify the problem and sort a solution.
So TALK please
Pace