Pineapple chunk scrog attempt

Looks like you still have a lot of space to fill in before you would flip. Your issue with the purple leaf stems looks like a phosphorus deficiency combined with yellowing lower leaves which is nitrogen deficiency. From your photos it looks like the main stem has purplish red streaks running up it. A nitrogen deficiency can also cause purplish red leaf stems and streaking in the main stems. I would try increasing your A & B to give her more of what she needs. You definately don't have a Cal/Mag issue and you should drop that back to a normal dose so you don't cause any other issues. Your ph should be a bit lower at 5.6- 5.8. Good luck

This really sucks and only your plant will be able to really know when she'll want to finish. Keep her on the 12/12 light cycle. Any further stress and she can hermie. Constantly verify to make sure no pollen sacs are developing while you wait for her to continue working on her buds. Keep giving her bloom nutrients this will also help to make the plant focus on the buds and revert back to flowering. Hope this helps.