Hair loss--whether it be from autoimmune, thyroid issues, postpartum, or otherwise--is not something people ever enjoy talking about.
Hair loss is disheartening and extremely stressful to deal with. As someone who suffers from Hashimoto's related hair loss, I know how troubling and painful it is to shed your hair.
The first thing you should do is check your thyroid level. Often the cause of hair loss is a dysregulated thyroid. Another potentially helpful test is a ferritin test, which will assess your stored iron levels, as iron deficiency is another a very common cause of hair loss. Zinc deficiency also goes hand and hand with thyroid issues and can cause hair loss. Taking a zinc supplement may help mitigate this.
Other supplements that can help with hair loss are collagen, biotin, or supplements specially designed for hair loss (such as Nutrafol). It is also important to get enough protein a day (60 grams for the average woman) and essential fatty acids, as a lack of these can cause hair loss.
Certain shampoos can help hair grow, such as PURA D'OR Original Gold Label Anti-Thinning Shampoo, and some leave-in treatments including keratin and argan oil help rebuild proteins in the hair.
If your hair is falling out it is important not to bleach and abuse your hair. I know it can be stressful, but stressing about your hair falling out will make it worse.
Hair will eventually grow back, when other things get under control. I hope this is helpful.