I love this little beast.. I think she might be figuring out her strength because this morning she broke a section of her cactus off from her plant and munched on it all morning
I actually got it at a flea market in canton texas about six years ago. It use to be just a couple of pads but now the size of a small bush. I have transported itevery time I've moved and I even divided it to grow in my sulcatas pen..
Optuna cactus is a common food in central and south america, you should be able to find it at latin markets or farmers markets here in the US. They call it Nopale or something (pronounced "no-pal-A") Grows everywhere so you should be able to find some locally.
Good luck!
--Jeff