Sorry to hear about your frustration, the pressure and pain. I believe that CK keeps the tumor from growing, and in some cases it will shrink. I suspect the doctor is not concerned because the tumor is not noticeably growing (there is a margin of error for MRIs).
Your exhaustion is how I was when i was first diagnosed. So tired, could feel my brain in my head (pressure) a few times / day, and was struggling cognitively. Due to the size/placement of the tumor, we selected surgery last August. (Just had CK yesterday, however, as the remaining piece of tumor got a bit larger). THe most elusive part of this experience are these symptoms that people cant see, and it never seems that anyone really understands how much of a struggle they are.
It may be time to discuss options with your current doctor. S/he could discuss the trade offs if you take a surgical route, as well as set expectations about the tumor shrinking.
Many positive wishes!