What Causes A Period With Less Bleeding?

I just wanted to ask..my due date ( monthly period) was supposed to be last may 23. On that day, I measured the amount of blood that came out of me though, it was only about two tablespoons for the whole day! and it wasn't really red. it was kinda brownish. then the next day, about, 1 tablespoon, and also light brown. On the third day, no more discharge... what could that possibly be?