Possibly Incorrect Current Reading
Since your circuit has a known resistance in it, you can avoid the meter burden voltage issue by calculating the current from a measurement of the voltage drop across the resistor measured with your meter in voltmeter mode, rather than by inserting the meter into the circuit in ammeter mode.

Of course, if your resistor doesn't have the value you think it does (manufacturing tolerance or human error in reading the markings) that determination will be invalid, but you can remove the battery and use your meter in ohm mode on the unpowered circuit to measure the resistor.