I'm still pretty new to primal but I've been no-pooing for years. I would guess the baking soda/dr. bronners is too drying for your scalp (hence the dandruff) and you're producing excess oil to make up for the dryness. Have you tried conditioner washing instead? Look for one with no silicone in it to prevent buildup. Suave Naturals and Trader Joe's Tea Tree are two examples.