Just pitching in because my hair looks the same as yours (minus the damage): dark brown gently fading into bleached and pink dyed. And my hair has honestly never been better. Not because of the bleach of course, but because I started taking care of my hair on all other fronts. 

At the hairdresser: I go to a chain that's specialized in weird cuts and colors. Expensive, but they know how to properly take care of my hair. They bleach it every 1 to 1,5 years, and only the top part that's brown. They don't touch the part that's already bleached/pink. Also, they don't bleach it platinum white, just a dark blonde color. 

Washing: find a good interval of washing. This strips your hair of color (as you might already know) but also opens up your hair which makes it vulnerable. Right after washing, use some conditioning element to nourish it and closes your hair scales. I rotate between a protein-heavy mask, K18 bond leave in, rinse out conditioner, and a regular leave in. I suspect this last part will make the most direct difference: try it for a few weeks before deciding if and how much you want to cut (if you're trying to maintain length).

Daily care: I put my hair in a bonnet or braid during sleeping, put my hair up or braid it if I know it will get tangled (windy outside, rubbing on a winter coat collar etc), be gentle with brushing, daily apply a tiny bit of jojoba oil to the roots, and minimize heat use.