OK firstly get a pot the same size your using and fill with soil. Let it dry totally and then keep that to one side as a pot to gauge weight against for watering frequency!
Then as said above stop chill and relax, your trying all at once with these girls and maybe worn ng against yourself a touch!
Also don't as a general rule listen to your hydro store! Your in the best spot for genuine aid
So in the beginning you were watering to run off, this isn't required when plants are young and in such size of pot. So soil was always wet and your roots will of suffered. Maybe switch to bottem feeding if wanting to develop your roots!
Then stop messing as you seem to be doing the usual thing when we all start out growing and over loving your plants!
Please also think about your re potting! Don't do this just as you hit flower! You want root development in veg and your plants focus on buds in flower not pushing out more roots. So last transplant min of 2 weeks before flipping!
Lastly your plants certainly should not look like they do with that leaf damage,so if your local store guy is saying otherwise, then you know he doesn't know squat!!!! To me maybe lack of oxygen for your roots?!
Your using a super soil which we know nothing about,so it's hard to judge the soil and its state, yet your running led so additional cal mag is always a must!
So work your watering frequency out once and for all against the dry soil pot. Then relax, less messing and second guessing. Once you sit back these plants grow themselves lol. If your PH is good and frequency of waterings is sorted and you add some cal mag all should come good (if your super soil is any good)
Wish we could help more but super soils are a pain lol