What is a normal amount of hair to lose per day?

Hair falls out every day, especially when you wash, condition, and brush it. But what’s normal and what indicates actual thinning? I noticed that if I go a few days without washing my hair or combing it thoroughly, way more comes off in the shower. Today (Tuesday) I washed my hair for the first time since Thursday, because it was curled. It also hadn’t been combed much because I just pinned it up at night to maintain the curls. It resulted in about a palm-sized hair-ball! It was pretty frightening. I don’t wash my hair daily, and I usually find a significant amount of hair in the shower (though today was probably the most). It may also help to know my hair is naturally very curly in texture and grows quite slowly. Normal loss or not?