1st I have to agree with the above 2 ladies, the only way to completely get rid of heat damage is by cutting it off.
I've transitioned from heat damage before, I spent a year transitioning, until I cut off all the damaged hair (which was everything but 2"). I no longer put ANY heat on my hair for any reason.
2nd once you get rid of the heat damage you'll be better at assessing your hair patterns/structure. It'll make caring for your hair easier.
3rd I recently purchased 'the science of black hair' this is a GREAT book to help you understand & grow healthy hair. I wish I had this book when I 1st went natural!
4th sounds like you're putting alot of protein in your hair. I have course, low porosity hair that does NOT like much protein. The book goes into detail with determining all this stuff. Best $25 I spent in the last few months.
5th anemia may stunt hair growth & cause thinning hair since the scalp and hair follicles aren't getting as much nutrients/oxygen ad needed (your body will distribute to the most important organs... And unfortunately, kidneys/brain/etc>>hair/nails.

Srry for the loooong reply