Adding more CYA will do no good. The bromide is consuming all of the chlorine no matter what form it is in (hypochlorous acid, hypochlorite or chlorine bound to CYA) as it is a cyclical process - the bromide gets oxidized by chlorine to bromine, then the bromine reacts with something (UV light, organic compound, algae, etc) and converts back to bromide where the remaining chlorine just reactivates it again. This happens until all of the chlorine is spent. Your ozonator is also acting as an oxidizer that is converting bromide to bromine (although it is very weak so it's not doing that much). This is probably why your sanitizer level never quite hits zero.
Please note - the DPD test reacts with any halogen (chlorine or bromine). So, when you are testing, your DPD indicator is really showing a bromine level, not a chlorine level...actually, you really have no idea which because it reacts with both. There is no test outside of an analytical chemistry lab that can distinguish between bromine and chlorine. So, when you get a result from your DPD test, it is almost always going to be Total Bromine, not Free Chlorine.
If water is cheap where you are, I would suggest you consider draining some of the pool and then rebalancing the chemistries towards the recommended levels here. It will take several partial drains to get the bromide levels down but, with each drain, it will be easier to maintain chlorine. One can certainly maintain a bromine pool, it just takes a lot more attention because when the daytime UV is high, the sanitizer level will drop very fast.