I also have hormonally-caused bladder issues, which have (knock wood) started to calm down in the past few months. For awhile my doctors were sure I had developed Interstitial Cystitis (IC) or autoimmune bladder inflammation known to be caused by hormone flux or infection. Doing research, I found one dietary method of treating IC is to avoid oxalates so it looks like you're doing the right thing. Even if you don't have IC (and I hope that you don't!) this should help soothe bladder inflammation.
Mine, I believe, was solely caused not by the Mirena, but by a horrible reaction to Progesterone cream, which I took to rebalance my system after Mirena was removed. It's taken nearly a year for the stuff to begin get out of my system. Bladder problems and brain fog only began with this cream.
In any case, sheer time and babying your bladder should help things!