We had a similar problem naming our newest ferret.  her name was Bandit
when we first got her, but we never called her that.  She just didn't look
like a Bandit to me, Criminal maybe, or America's Most Wanted Stinky Head,
but not Bandit.
 
So we just walked around for a couple of weeks calling her "the little one"
and trying to think of a name, much like you and your "little old lady".
One day she did something very ferrety, like jumping on the table from
nowhere and we decided that she must be a Jedi master.  How else could she
have done it unless the force was with her?  :) So, we went from "Little
One" to "Litl Wan Kenobe", or Stinky Head for short.  Most days, it's "Litl
Wan".
 
The moral of the story; what's wrong with "Old Lady"?  Sounds like it fits
her pretty well.  Or you could name her after my Grandmother, Matilda.  :)
 
Britta
 
Yoshi
Tie (Necktie) (Can you tell that our ferrets earn their names?)
Quincey
Kelsey
Litl Wan
[Posted in FML issue 2553]