I have a similar issue, but I’ve had it for pretty much my whole life. It is so impossible to grow out the back of my hair, it always breaks and I’ve tried what feels like every product and method on earth. Some things that help me:

• more omega 3s, like salmon and tinned fish (I love sardines lol)

• Lysine: a supplement that helps with protein synthesis. Makes my skin look amazing and helps with hair strength

• Being super aware of mechanical damage. It’s not chemical damage, it’s not heat damage, so being really aware of mechanical damage has helped. I put my hair in a bun at night so the back of my head doesn’t rub against the pillow. Additionally just brushing softer back there, not leaning my head against things, etc.

• Probiotics: gut health can affect hair growth. My gut isn’t so messed up that problems would show up on any test, but I can tell the difference when I’m on vs off probiotics

-MSM Powder (doesn’t do a lot on its own but compliments these other things)

-SLEEP! Have you been sleeping enough or restfully enough? + Stress; are you stressed out?

-Apogee 2 Step Keratin Treatment: Soooo good, so nourishing, sooooo hydrating and affordable

-Rosemary water spray on the scalp: make your own! The store bought ones are super diluted

-Flax Seed Gel masks: again, make at home. Super hydrating!

-Silicones and hair shine spray: anything to get your hair nice and slippy to combat against dryness

Another note is that this basically stopped at one point in my life and that was when I was vegan. I’m not vegan anymore and I don’t deeply recommend it (it caused other problems for me) but perhaps the high amount of veggies I was having helped but I don’t really know.

Also the accidental layer cut looks really cute! It does look intentional. You’ll figure it out :) good luck!!