The way I know I need protein is when my hair is flat and limp.
When I was washing with sulfate poo's my hair would always be voluminuos (sp) and bouncy. Doing CG my hair isn't quite so bouncy and full of volume, but when it gets particularly flat and lifeless and I feel like I want to use a sulfate shampoo to get that volume back, I reach for the protein and my hair is as good as new!
Just remember to rinse with ACV and do a DT right after!
2c/3a/3b Fine/med texture, normal porosity, normal elasticity