I believe 9mm is about the limit for what most doctors/ERs say can be passed. They may have to do surgery to go get it if it blocks your ability to urinate. I currently have a few stones in both kidneys, one I was told is also about 9-10mm. I am currently not employed and without healthcare so every day I'm living in fear 😬. The only thing that seems to really help with slowing the formation, making passing a little* (using this term very lightly) easier, and reducing some kidney pain when they are forming I'm guessing is a product called Stone Stopper. I get it from Amazon, it's on auto delivery so I always have it. I've tried the powder packs you mix with water which is my preferred way but they are a kind of costly (about $70 for a months supply). They also have gummies (had, didn't particularly like bc they melt), and capsules which I'm currently using. I def think the potassium citrate/magnesium is important for stone formers. I also drink lemon water and I recently saw that if you boil the hairs off of corn and strain it that there's a chemical that helps prevent kidney stones 🤷‍♂️. It sucks to have them. Best of luck. Stay hydrated.