Antihero
Best bet is to have her try out a P11, if possible, just to see what she thinks about it. Not sure as to how much larger of a gun she wants to go to, as the P11 is a pretty small 9mm. To me a midsize 9mm. could be anything from a Glock G43, to a G26, G19, S&W Shield, S&W MP9c, Ruger SR9c, or Springfield Armory's XDm, XDs, or XD MOD.2. All of these are relatively compact pistols but still somewhat larger than the P11.