Sorry that I can't give you a really concise answer, but with some products my hair sheds like crazy too. Especially when I have lots of build up. Back when I used to use bumble and bumble I was shedding like crazy, no visible thinning though. Devacurl also made me shed. I suspected some type of specific protein sensitivity but I could be wrong, although I stopped using them and now I dont shed at all. Actually looking back I think they both contain hops....hmmm.... Anyways, check the ingredients lists on your products. You could have a protein sensitivity, even if your hair loves other proteins (mine certainly does).
3a
medium/thick
Loves protein and oils

Low-poo: MopTop gentle shampoo
Co-wash: CJDF, Jessicurl Aloeba
RO: Jessicurl Too Shea, MopTop daily conditioner, CJ rehab, CJ strengthening
LI: ^^^
DT: Jessicurl WDT, SS Deeply Decadent
PT: SS protein treatment, Ouidad 12 min
Oils: argan, sweet almond, jessicurl oil blend
Stylers: SS firm hold, SS curl enhancing jelly, Kiss My Face Upper Management gel, AG Recoil