If you never pass a stone for it to be tested, do you just never find out what's causing them?

I had a kidney removed in 2022 because a staghorn stone had been undetected long enough for it to make the kidney unsalvageable. I've been maintaining the health of my remaining kidney with annual follow ups with my nephrologist and my urologist. My Nephrologist makes me do a 24 hour urinalysis, a CT scan, and blood work every year all before my follow up appointment to discuss the results.

Unfortunately, since the hospital that removed my kidney did not do tests to figure out what the stone was made of (I stupidly didn't think to request testing), it's difficult for my doctors to fully help me prevent stones. I do have two or three tiny stones in my kidney but my Nephrologist isn't concerned about them because they're small and not growing. I've never passed a stone so I can't bring one in for testing. I did do genetic testing in 2023 to see if there would be an answer (sometimes stones are based on genetics apparently), but my Nephrologist reviewed the results and said they didn't appear to suggest that my stones were genetic.

Last year my 24 hour urinalysis results weren't very good for the first time since I started having them done in 2022. I drink 80 oz of water daily and I try my best to limit chocolate, salt, etc. I do drink one can of ginger ale and a hot coffee too. No other drinks. I also use the treadmill once daily for an hour (fast paced walking on multiple inclines). I'm nervous and upset about my results from last year and my annual appointment is coming up so now I'm freaking myself out. It feels like I'm at a permanent disadvantage because I have no way of knowing what's causing my stones. My Nephrologist has told me that even with the blood work and urinalysis all he can really determine is what \*may\* be causing them and what \*may\* help prevent them because we don't know what my stones are made of. So basically I could be doing everything I possibly can but in the end I can't really prevent stones effectively. I realize that trial and error are how doctors determine a diagnosis or solution, which is fine. But the way it was explained to me was that if I had a stone tested then that would remove most, if not all, of the guesswork.

Do I have to just accept the fact that trial and error is all I'll have to go on? Are there questions I should be asking my doctors that I haven't thought to ask?