How is it possible for females to "shed" SO many strands of hair on a daily basis and still retain a relatively normal looking head of hair?

I'm a 22 year old female who sheds. so. much. I have pretty long hair, and I have a lot of hair, but it's really thin. It always makes me so nervous when I pull out loose "clumps" of hair after I shower or what not... cuz like... hair is not infinite.

Since hair clearly can't regrow as fast as it's lost, how does our hair still look the same? Won't it run out eventually?