Mine is also much straighter. Part of the problem is genetics, part I believe is that the area is drying out faster than much of the rest of my head, also plopping on top of my head pulls it straight so I never do that. Roller jaw clamps help somewhat, both before and after diffusing to partially dry, also I cut an inch off my underlayer!
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond/ fractionated coconut oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Au Naturale styling gelee
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect