I'm no expert, but I can certainly sympathize. I have the same hair coloring history that you do but with a few more years (I'm 45), and I get the same permanent until washed ponytail dent. I figured since I have colored for so long, I must be highly porous, but I had a hair analysis done by Live Curly Live Free, and they said that my hair is medium porosity. I didn't quite believe them, so I have done a couple of gelatine protein treatments. They make my hair super soft, it loses all the wave, and gets super frizzy. I did my last one on Friday, and realized that I really DON'T need protein! I read all my product labels and dropped all my protein products and I'm adding as much moisture as possible. Thinking about doing a deep treatment of some sort.

Currenly I'm using Suave Naturals as co-wash, GVP Conditioning Balm as rinse out (left in during my shower), then adding a bit back for leave in, and using a tiny bit of BRHG for hold. I'm thinking about trying silk or keratin at some point, but not any time soon.
2C/2B; Med-fine texture, Normal porosity/elasticity, med-thin density; Color treated
Cleanse: Jessicurl GLS, L'Oreal EverCreme cleansing conditioner
Co-Wash: SNES, VO5 Kiwi Lime
RO/LI: Jessicurl Aloeba and TooShea!, KCKT, GVPCB
Stylers: KCCC (HG!), SM C&S Milk, BRHG, Jessicurl Gelebration Spray, Confident Coils
CG since 4/23/12
Located in Houston, Texas

"Hair really is the crowning glory of a woman. It lights up her person, it frames her face, it makes a halo around her." - Ann Harding