You have the same properties that I have. I don't think your over proteined, either. I, too, feel that it's the polyquats. Polyquats coat my hair and prevent products from absorbing. Don't know what you used to clarify, but it may take a few sulfate washes to remove them. Read your ingredients carefully. Lots of shampoos have polyquat 7

IMHO, low porosity hair doesn't tangle as much as other hair because the cuticle is tight. Since it's your ends that are matting, it may be an indicator that you need a haircut.
3a (Corkicelli), highlighted, fine, low porosity

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me, Aloe Fix