Please give me my extra s!

I know I bang on about punctuation, but one of the things that annoy me the most is the way people puctuate the possessive of a word or name ending in s. Thus, anything belonging to me becomes Frances' as oposed to Frances's. I am not the plural of France; I just have a name that ends in s. I would love to have been called Catherine (because I like the name, but also, it doesn't end in an s. And anyone with the name of Catherine is unlikely to be called Sir or offered Russian brides, both of which frequently happen to me). Also, I  don't much care for my own name, but I'm stuck with it. (I'm often Fran, which doesn't end in an s, and is more friendly.)

So please, if it's mine, it's Frances's. Okay? Thank you.