Autos grow and flower regardless of light schedule. My Gorilla went 15 weeks from start of germination. Reducing the hours would only shorten the available light available and the light is the "food' that plant uses to grow, the nutrients help the plant metabolize the light into growth. 6hrs darkness is sort of the sweet spot for plant rest. Your diary says this is an indoor grow but your plants are outside in the pix. If your moving your plant in and out of the tent that can slow the plant down. Growers choice seeds are slower than many other auto strains. Your plant looks healthy and on its way to making good big buds. Patience and consistency is a key ingredient.