Yes, you aren’t getting enough fluid. Yes, kidney stones form when urine becomes too concentrated, because you aren’t getting enough fluid. Yes, it’s harder to get enough fluid without a colon. You should be peeing light-colored urine, enough to fill your bladder at least several times per day. Since you now know that you are prone to kidney stones you’d be better off with more dilute urine than that minimum recommended amount.
There are lots of ways to keep yourself hydrated, even when life makes that challenging. It’s usually better than kidney stones. Good luck!