Wire the light with 12-2 wire, or run the 14-2 to the next outlet that is protected with a 15 amp breaker.
#14 wire is rated for 15 amp max. Putting it on a circuit that is protected with a 20 amp breaker is a no-no.
Why is there 12-3 at the washer outlet? 12-3 would indicate you have a black, red, white, and copper ground wires.