If your assumed pax weights are wrong, your Vapp will also be wrong. If the Vapp is sitting right above Vls, I'll add a few knots, just in case.
3kts shouldn't make you unstable. In our books, the airspeed requirement is within xkt of the TARGET speed. So even if you added 15 to Vapp, and GS mini added another 10, as long as you're within xkt of the target speed, you're technically stable. May have to adjust your flare technique in that case though 😊