Why are you chomping at the bit to defoliate? Defoliation is only called for when you need to get air flow through the plant because it's too dense and humidity might be a problem OR you have a lot of lower bud sites that aren't getting any light.... This plant doesn't look so massive that it needs it. Instead, I would worry about your pH problems and the deficiencies it's causing because THAT is going to limit your harvest big time. A pH of 5.5 in soil is far too low and your plant can't get at the nutrients it needs. Bring it up to between 6.0 and 6.5 like NOW... She's got a lot of problems that this is causing.
Good luck....