If you are growing all autos your plants should do better under a 18/6 or 20/4 light cycle. I do have some autos under 12/12 at the moment but that’s only because I’m also growing photos. Before adding photos to the mix I ran my autos under a 20/4 light cycle from seed to harvest. They loved it! Also, regarding nutrients... Autos are a bit sensitive to nutrients. My autos ran into some nutrient burn issues when feeding nutrients at full strength, they seem to like 1/2 strengh much more. But overall i think your girls look well loved, keep it up!