My CCW class instructor strongly suggested against any sort of purse/backpack carry situation. If the backpack/purse is stolen, you're fucked, and so are all of the people that weapon is used against.
You should just carry it on your person, or not carry at all.
I, myself, use a clip-on "pocket" hip holster which goes inside the pants and clips on the outside. It's not actually on the hip, but in the front of my pants, barrel cleverly positioned away from the goods in case of an unlikely accidental misfire.
