Sometimes people tell you that you had a good impact on their lives.
Other than that we have our standards for goodness.
Some don't really care for making the world a better place, rather just live their own lives.
I just care about people whom I am close to(not many, and none around anymore), but it doesn't mean I don't try and show kindness to whomsoever I can.
I guess you will have to judge for yourself or see if someone thinks you have made the world a better place.