Instead of straightening, why don't you try twist outs or braid outs for more "wavy" looking hair? Honestly, I would kill to have 3b hair.
2c-3a - coarse - normal-high porosity - high density - growing out to donate

NP/LP: KMF Whenever Conditioner/ YTCucs
RO/LI: Sevi Pumpkin Seed DC / CJ Argan & Olive Oil, KCKT, YTBbs
DT: Coconut Oil + scalp massage
OIL/STYLER: SM Elixir / KCCC
COLOR: henna, amla & indigo