Have you seen your family doctor or a dermatologist? Are you eating a nutrient dense anti inflammatory diet and getting your 10,000 steps every day?
One thing that comes to mind is that you mention several things that can irritate or damage the scalp and contribute to shedding - hair dye, sulphate shampoos, hairspray for example. You might choose your products for scalp health as much as, if not more that, hair health.
Is there any reason you cannot wash your hair more than once a week? That would remove any sebum which can be irritating to the scalp, and an extra chance to condition and treat your hair. Beneficial ingredients for damaged or porous hair include hydrolysed protein, coconut oil, ceramides and panthenol.
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
CO-wash: Inecto coconut
Treatments: Komaza Matani, coconut oil, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume, Inecto argan
Styler: Umberto Giannini jelly, Boots Essentials gel
Experimenting with: going back to basics