Extract from question : -

• You didn't alter Rs in the denominator to account for it having an uncertain value.
• Putting the numbers into the formula (corrected or not) does not give 3.15% by a long way

Sanity checks: -

• If Rs increases by 3% then the current through the meter rises from 50 uA to 51.43 uA when 1 mA feeds the circuit
• That's an error of 2.86%

OK I agree with part 1 of your answer. But part 2 seems all mixed up. Extract from question : -

• You didn't alter Rs in the denominator to account for it having an uncertain value.
• Putting the numbers into the formula (corrected or not) does not give 3.15% by a long way