Cut it. Anything that even gets close to dying I cut off really. Just sucking energy. They're plants, they will always grow more as long as the whole plant doesn't die.
I'd say just treat her like a normal plant for another couple weeks man. That whole revegging and the crap it endured in the beginning do take it's toll one way or the other in the end.
Okay, I reread your post and I think you're doing okay. I think you're getting over anxious about when they should be done. How long have they been on 12/12 cycle? More white hairs coming out usually means buds are still getting bigger.
I usually start them in a smaller pot, move to a medium pot, and transplant a week before flowering them to their big pots to grow during flowering.
Seems to work fine for me.
They should be but I have a plant that's much bigger than yours in a pot that's smaller than yours. It needs transplanting but it's doing fine. They don't HAVE to be transplanted unless they become rootbound. You should transplant before then though :lol: