Clearly she's heavily stunted, yet she is sho...

For starters work with what you have. Personally I think topping/ fimming small auto flowers is a waste of time. Their life span is so short you lose valuable vegetative time/energy when you top. If she was a XL or XXL variety and you had limited room it would work. LST is the way to go. Your ph of 6.6 could be part of the issue it's too high for soil less you should be down around 5.7 to 6.0. You should also be checking the ph and TDS of your runoff to give you a better idea of whats going on in the root zone. The lower ph would have helped the roots take in more nutrients. I also think you may have been under feeding her. I'm unsure about the N-P-K ratio of your nutes but you may want to tweek your regime by either increasing your nutes or using additional beneficial products. Don't be fooled by the size of the plant sometimes the smaller buds are the most potent. Good luck