facebook privacy help?

[empathy]

I have my facebook set as privatly as I can but my Mother just showed me her facebook account and I was disturbed to see how much info about me comes up in her home page. All of my comments on peoples walls and photos are visable, and these are people she does not even know and is not friends with! I do not want to prodcast to everyone every time I comment on a friends status or photo. It has put me off writing ANYTHING on facebook now knowing its going to come up in everyones wall. Its weird though, I can only see things my friends write to each other and I thought thats how it was for everyone. Why is my Mother seeing every little thing I put on anyones page even though she is not friends with these people? and how to I change my privacy settings to get it to stop announcing to the world that I like someones photo or status. Its disturbingly stalkerish.