Shouldn't we look at hair loss solely based on the amount of hair falling out?

These days, after washing my hair
I end up checking the hair collected in the drain first.

It seems like the amount of hair loss has increased.
I also feel like the top of my head looks thinner than before.

However, depending on the lighting or hair parting
It is difficult to judge because the degree to which the scalp is visible has changed.

I'm actually getting anxious from just keep searching.

To check for hair loss, not only the amount falling out
What changes should we look at together?