Hi
This has happened to me a couple of times over the last, wow, 15 years!
My hair is naturally straight, brown, caucasian hair.
I have it coloured Swedish blonde, have done for so long that most people have forgotten I'm a brunette, or didn't know me then!
Most of the the time, I've had very light ash blonde colour with lots of highlights, so bleach for that lift, throughout. My hair has been long, bra strap long, and it lovely condition. So it is do-able!
Three times I've had catastrophes
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When I started having it coloured, a hairdresser put peroxide over the same hair more than one, before I knew to say "are you crazy?!". It ended up all completely broken and trashed. Lesson learned.
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I was unwell and twisted my hair in a top knot, day and night, with a band, for months. It broke around the parts where the band had been. Lesson learned
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At the moment, good god, driving me crazy. I moved countries and languages, it took three attempts to find a hairdresser who would actually listen (blonde isn't a popular here so they don't bother), that lead to all sorts being put on my hair, I still don't even know what, plus needing a couple of corrections. It pretty much all broke of eventually, it was fragile. Lesson learned this time is that once it's damaged, it's damaged and it will break, can take care of hair in advance but once too much damage done, it will eventually go. I was confused because even six months after, my hair was still breaking, but the damage had been done, it may not break straight away, but it will eventually. So it can be confusing, what's going on, I'm not doing anything different, but it can be damage from a year ago catching up.
For my usual super shiny healthy very coloured hair, to take care
I don't use straighteners or any heat other that a cool upside down blow dry. I know that no straighteners are not an option for some (just as sorry, but no colour is not an option for me!), it doesn't sound as if you are over using them at all. Have you checked to make sure there isn't damage being caused because of hair being wet, or certain oils or products in it when you straighten? I'm not an expert as I just don't straighten, but I have heard things about having to be very careful about products in hair.
I put argan oil through my hair before drying and that makes it so smooth and silky, I really recommend that, if it's ok with straightening!
No highlights over highlights, ever. Some colours are actually good for your hair, the conditioning ones, but not anything that lightens a lot.
I wear in down as much as possible, including to sleep. If I have to put it off my face for gym, I use a really loose scrunchie for most of it and leave all the parts around my face out. Parts at the cack I also leave out, I use a hair clip to loosely lift them up.
Silk pillow cases are not expensive and help with general appearance of being smooth.
Meanwhile, at the moment in start over mode after my hair was trashed
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I'm getting rid of as much damaged hair as possible, my hair is way shorter than I like it, but at first I left damaged hair and it broke eventually and the split end travel up making things worse. So one day had to start going for the chop.
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Coconut oil treatments, I thought it was a fad, turn out wow it works. I really recommend this, good for all hair types
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Biotin supplements and vitamins, my hair is growing in a bit more quickly and definitely way stronger with this (also my nails are in super strong grow quickly condition). I'm thinking my hair will be stronger in future so will handle more, plus it's growing in well and a bit more quickly, so I can get rid of more damage.