Sadly I think your son may be right...

Words can take on new meanings. And the problem is that the only people who really tout being a feminist any more seems to be man hating lesbians (I am not implying all lesbians hate men), and women with a serious chip on their shoulder.

Your definition is definitely the correct one, and I consider myself a feminist by that definition, (another misconception is that men can not be feminists) but the fact remains that people who simply want equality for both sexes rarely (or at least not loudly) refer to themselves as feminists...