Just my two cents. From your check list, you use Espsom salt every two weeks or so. Thats too much. Too much mag can can cause salt build up and lock out nutes. If that was the case, then your plant would have sympotoms of ph lockout (a lockout is lockout lol). Flush your plants, rinse some of that stuff out and dont give it anymore. Ride this out to the end and I think you will be fine.