Well, she's still quite vigorous - that's great. The fact you amended the soil is positive too.. I was thinking the transplant may have been too "hot", meaning the soil was too fertile for the small plant.. The new growth looks good and the deteroriation appears to have slowed down as well. You can feed (and I recommend, but it's up to you) Root Juice (you did get it, right?) the entire grow, start to finish - it's practically NPK free and just keeps inoculating the soil with mycos. Everything I've read about BioBizz says to feed low dose Root Juice from the start and work your way up to full dose. It's not a fertilizer as much as it's a root stimulator.
I believe you may be correct in waiting too long to transplant her, as long as you're adjusting your water I think she'll continue to rebound. Do you feel she's starting to look better or not? You have the plant in real time and I'm just comparing pictures to pictures.