Definitely no more colouring because the process will create even more chemical damage. Even semi- permanent lift the hair cuticle a bit to get the colur to take. Avoid.
If its breaking off, your hair needs the bonds that have been damaged to be repaired. Olaplex does this, but given cost concerns, try Pureplex intensive repair treatment (superdrug).
Your hair will also need hydration... try hair masks that are described as 'moisturising'.
Use a leave-in treatment as well to protect your hair day to day.
No heat styling, that's heat damage plus mechanical damage (from brushing/ wrapping the hair).
Get a trim as short as you can bear to prevent split ends travelling up the hair strands.
Silk pillowcase/ bonnet helps prevent more physical damage.
Try to minimise any touching of your hair e.g. loose plait (no tension) silk scrunchie/ low ponytail (careful not to make band too tight, that can cause breakage too) and just leave it alone.
Over time, it will improve - and grow!
Good luck.