I've gone back to regular shampoo!
The baking soda seemed to be causing breakage where my highlights are growing out. I tentatively blame this on the weakened hair that was dyed, but after I grow it all out and have less fuzz I will have to try again and confirm if this is the case.
Meanwhile, I am still using apple cider vinegar for shine and conditioning. As a bonus it doesn't attract bugs the way perfumed conditioner would, which is ideal as I'm working outside on the farm this season!