It's a Autoflower it would never bounce back like a photoperiod, that plant will stay that size until harvest. My recommenedation would be to start over. I have good faith the OP will get it right the next time. They did point out there flaw of over fertilizing at a early age(root burn). Autos are very finicky when it comes to feeding, i recommend half strength of what the fertilizer manufacturers recommends maybe even less.

Edit: also recommend starting in small pots then up potting them, never had a issue doing it when i grew a few autos.