When I had to go through a transitioning period after I chemically straightened my hair, I just cut the straight parts off bit by bit, took quite a few months. Since you probably only have heat damage, a really good conditioner and deep treatments will go a long way. One I really like is mixing olive oil and honey with conditioner, maybe an egg or a banana for protein. I usually DT after I've straightened with a flat iron to counteract the heat damage. Hope this helps!
Dense, fine/medium texture, low porosity
Low-poo: Elacel Aloe Vera Shampoo/ Devacurl No-Poo
Conditioner: Inecto Pure Coconut Conditioner
Leave-in: Devacurl Set It Free
Styling: Pantene Curly Spray-Gel