About LST / Main-Lining

Main lining involves LST so yes, you are actually using both principles, although LST on its own does not necessarily involve topping. Also, 18/6 is better for your plants, they need sleep to function properly. Don't worry, growth will be identical, if not better with more sleep. Ease up on the nutrients, they are very, very dark green, half to three quarters strength nutrients is usually plenty. Do not defoliate, - less leaves = less energy being made = less growth. Since they are autos and considering what you have already done to them, I would just leave them to do their thing without further interference. Nice job though.