Hi Colin
Have you questioned why you are taking Oxybutinin ? Are you dry at night completely ?
I agree with Lynn, ask for uriflow tests. Are you actually emptying ? - ie easy to do yourself, flow etc .. just time flow into container.
Just looking at what you have posted. Every half hour ? > 20 times a day ? (20 x 100ml = 2 litres) Are you drinking a lot of caffeine ?
I have been lucky, full control (better flow than before op)
Average day will be : dry at night (8hrs ish) 5 - 7 times a day (I empty about 300 ml max in about 20 seconds)
Flow rate is around 10 ml per sec as you age over 60+, bladder 250 - 350 ml ish - you can do the maths to empty
(probably >20ml per sec as a teenager !). I've never measured total volume in 24 hrs, it should I understand be around 1500 - 2000ml.
I have noticed I do however get the the urge to go (and still do) a lot earlier than I used to (which I ignore).
I hope you are sorted ... some simple tests should give you an idea on how much your urethra is passing, it should help to diagnose what exactly may be happening. ie in my opinion , get some metrics.
Regards
Gordon