I like to travel light.
I bring about the same amount regardless of the length of my trip. I try to bring carryon only. And I've taken a number of overseas trips of one, two, three, even four months in duration.
I usually succeed in carrying everything on. My rollaboard, packed, typically weighs about 10 or 11 kilograms (20 to 24 pounds); I also have a largish purse and another small bag which can piggyback on the rollaboard. Sometimes I am forced to check the rollaboard -- intra-Europe especially. (There's usually an eight-kilogram limit for carryon there but....) Another strategy I have to use (especially in USA) is to stick my purse inside the small bag, at least for purposes of getting in the security line (two item limit for carryon).
Kathy