Huh... a subject I can contribute to.
Having dealt with stones for around 25 years (biggest was 23 mm, after lithotripsy it was like passing 1000 stones over a 2 week period) I could write pages and pages on this topic, but I'll skip straight to my top conclusions:
--> listen to your urologist, and then go see specialist. Urologist is great, kidney stone specialist is better. Get the extra blood tests, etc etc.
--> None of the home remedies worked for me. None. Not at all. But yes I still avoid teas, and drink lots of sugar free lemonade.
--> If you are not peeing every couple hours, you are not drinking enough - flush the kidneys constantly. Its a pita, but nothing compared to a stone, nothing. Drink. More. Then keep drinking. Then drink more. And if you're a beer drinker remember that alcohol dehydrates you (which is bad for stones) so drink 1 full glass of water with every beer.
--> Calcium oxalate stones - years ago they told me "No more calcium - no milk, no cheese, etc." Now they say that wasnt right, the problem is that when you eat foods with either calcium or oxalates, make sure you have both together so that they bind in the gut and never get to your kidney. (google that, IMO its kind of important.)
Bottom line is that they dont really know the precise cause or prevention. At least not that I can find.
So for me, I drink drink drink; avoid calcium and oxalates but when I have them I have both; drink some more; and be thankful that modern medicine can prevent the stones from killing me and can prescribe drugs.
Good luck, I feel your pain.