My attorney keeps telling me that my case is clean and well prepared, but it’s been quiet for a long time and people who filed after me seem to be getting approved already, so I’m wondering if this kind of uneven timeline is normal or if I should be concerned that something is holding my case back.

Yeah, that kind of uneven timing is very normal and usually not a sign that something is wrong with your case. USCIS doesn’t always process cases in strict filing order, and approvals often depend on which officer or office gets the file, current workload, or internal priorities, so people who filed later can move faster just by chance. If your attorney says the case is clean and there are no requests or issues, it’s most likely just stuck in a slower queue rather than being held back for a specific problem.