why does my hair not ever get straightened?

i have very thick curly hair (3c) and ever since i was a kid i tried to straighten it. ive accepted my natural curls mostly because my hair is basically impossible to get straight. i have tried everything, from blowouts to hair straighteners and even both at the same time. ive even asked a hairdresser friend to straighten it and it just never looks right. i have always used a heat protector (idk how its called in english) and yet, when my hair gets “straight” it looks extremely dry, frizzy and downright horrible. also, since i have a really long fringe to hide my ugly ass forehead when i straighten out my hair its almost chin length, and i dont usually part my hair at all. i tried side parts and middle parts but i still end up looking like a blonde lorde farquaad from shrek. i like my curls but would like to wear my hair straight every now and then and not have it look terrible. does anyone have any advice?