Actually, I think texture is a better indicator of protein sensitivity. My fine/low porosity hair LOVES protein.

You don't mention what products you're using. It would give people a better idea of what the problem is. Do you use shampoo?? DT?? Use products with a lot of chemicals?? It could be anything.
3a (Corkicelli), highlighted, fine, low porosity
SE PA

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