Thanks for the answers. Helps a lot.

If you have high CSF pressure, a puncture would usually show some quick relief but if the cause continues, the pressure would return within a short time. But, there are symptoms of elevated CSF pressure that you don't appear to have.
Intracranial pressure - Wikipedia, the free encyclopedia
Have you even found a neuro willing to do a puncture ?

A NeuroPsych would need to do at least a minimal battery NeuroPsych Assessment. 4 hours of testing would usually be required. Trail Making, WAIS II, Wechsler Adult Memory, and an MMPI-II would often be the minimum.

Volleyball risk may be low but if you are dizzy, those risk factors change. Most return to play assessments consider dizziness a serious risk factor for a repeat concussion so you should be careful about playing while dizzy.

How is your sleep ? Do you fall asleep easily and wake easily ?
Sleep could be a big contributor to your symptoms. Proper sleep can make a big difference in how the brain handles fluids.