Your input should match your output ideally. So if you DRINK 64oz throut the day then you should pee out about that much in about 24 hrs.
How high is your bp? are you checking this as well? I would call your doctor asap and tell them you are not producing enough urine They might want to check your kidney function. Good luck to you
Are you drinking enough? Your urine should be commensurate with your fluid intake. I would up your liquids to see if you can get more out. Also, maybe you aren't completely emptying your bladder (it is harder to empty the further you get)...a tip for emptying your bladder is to sit on the toilet, go pee, then try to touch your hands to the floor between your feet...this puts your bladder in a different position...and try to pee again...
Good luck!