Like you, my experience with keratin did remove all of my curls.
Self-applications performed between 2009 and 2010 permanently changed my usual volume of ~3b fine, yet healthy curls, into limp 2a soft waves. My hair still felt/looked healthy but it was lifeless and flyaway ... exactly like baby hair.
The limpness paired with my baseball shaped head made me look ridiculous!!!
I did see some roughness, frizziness, and breakage during the grow out, which has been over the last ~ 2.5 years. To combat those issues I stopped using shampoo, amped up my conditioning routine and started wearing my hair up ~70% of the time.
Also, by following the advice from ladies on this board I found a regimen that allowed me to grow ~2b/3a hair to almost waist length.
But for the last 5 or so months I have experienced an amazing amount of thinning. Half my hair has fallen out, for sure.
A couple of particularly douchy coworkers started making fun of being able to see my scalp in July/August, so figuring it was keratin related (because Coppola made me shed pretty bad in 2009) I stopped using the Qod Organiq I'd been using for 2+ years. I also started taking a bunch of vitamins.
At the beginning of this month I finally went to the doctor and got my blood work done. When my blood work and other tests came back normal I started researching and found some interesting information.
Somewhere on a long hair site (will post link to it later) someone mentioned that a shock to the body makes hair fall out. They claimed that the shock could come from diet, exercise, accidents, stress, hormones, etc.
That made me remember that ~ 6 months ago after watching "Fat, Sick, and Nearly Dead," I quit eating sugar and bread cold turkey and started a pretty strict juicing regimen. My diet for the last 13 years has been HORRIBLE, so the fact that my hair (and acne) issues cropped up when I drastically changed my diet makes sense to me. Apparently diet related shocks often result in wonderful regrowth. Of course I didn't stick to juicing so that's annoying. But the good news is that despite losing a lot of hair I do have a "normal" looking amount left AND it seems the my hair IS recovering.
Upon inspection this morning, I saw a lot of various length new grey hairs (yay!) and decided to come to this site to refresh my hair color knowledge and figured I'd check out the keratin posts as well - which is how I saw your post. This is my first post to this site!!
The point of all this rambling is to say that being nicer to my hair definitely allowed me to grow out the damage I did by overdoing keratin treatments. So I'm pretty sure the damage you've experienced can be remedied.
And I think my thinning has been from the shock of drastically changing diet, not keratin ... and even probably has something to do with my getting older (3
Do you suspect anything else besides keratin for your thinning?
In the process of typing this post I colored my hair and am now sitting with Qod Organiq air drying on my head. If anything goes awry (like me suddenly going bald) I'll (briefly) let you know.
I do have to say that I almost detest the smell of this stuff. Why is it banana scented?! Blecht! Does anyone know of a non formaldehyde keratin product that doesn't smell horrible?
A few sites that helped me (or made me feel a bit better whilst trying to figure out how to stop the thinning) include:
This, the Naturally Curly Site
Tiffany Espinoza's youtube channel. She says to take folic acid, a hair and skin vitamin, and wear your hair up all the time.: Grow your hair long, fast! - YouTube
Long Hair Community had info about shocking the system and hair falling out:
The Long Hair Community
I love doing research and writing (obviously) so would be happy to help you figure out what's happening with your head.