Jeanette, have you heard of the Christy sliding knife?

It seems to match all your criteria;

Single hand opening
Locking blade with multiple positions
Small and slim so it should fit in even a woman's pockets.

Not trying to be mean here just saying I've noticed pockets on women's clothing seem to a lot smaller than men's.

Also the blade can either be sharpened or replaced if damaged.

Hope this helps