Hey buddy. For one, you can't do much to switch an auto into flower. They run off their own clock. Yes condi and environment plays an overall roll in your plants switch. But doing a 12/12 Will not help. If anything autos love more light. For my flip I done a 15/9 coming off an 18/6. And even with that you can run an auto from an 18/6 from seed to harvest. By looking at your plants pics your grow is showing serious signs of marconute deficiencies. Meaning your new growth is sucking mobile nutes like N-P-K out of old growth as it's finding it hard to find enough in your substrate. You should increase your N just enough not to much and focus on P-K for your flowering and autos need more micro nutes cause of the ruderails, (micro nutes)
Feel free to DM me if you want more info on what your plant will need. Happy growing.