One reason I grow Photoperiods so I can clone them and have more reliable results. AutoFlowers sometimes do not "auto flower" and require a reduced light schedule or even 12/12 lighting. I grew them for a year or so when they were hyped up and realized I was just paying more for electricity and having less consistency in my crops.
I would look into growing photoperiod feminized seeds from a reputable seed vendor like blimburn, north atlantic seed co, etc.. Clone the plants, send them to flower as fast as possible and whichever one performs best keep cloning it and grow it out big.
You can't clone autoflowers, you gotta pop seeds every time so the results are going to be super unpredictable just like you describe. New genetics will do the same thing, but once you have a clone it will grow just like the last plant every time and then you can actually dial in your setup.