I carry a double stack Glock 26 for CCW use. My better half carries a single stack S&W Shield (both are loaded with Speer Gold Dot 9mm ammo). She gets two rounds less than I do, but she feels that her gun conceals better with her build.
Incidentally, you can shoot just fine with either of those guns. I've shot her Shield on a 75 yard IPSC target with good success. I've shot my G26 to 100 yards on occasion (just for poops-n-grins). I actually think I might be more accurate with her Shield than I am with my Glock, but I've only done limited side-by-side testing so far. Obviously those aren't the ideal ranges for either of those CCW guns, but they will certainly do very well at normal defensive distances.
Anyway, everything is about compromise. You can go even smaller, and step down to less effective cartridges, or you can go to a single stack and stick with a more effective cartridge. Shot placement still makes more difference than anything else. My woman is 5'3" tall and 103 lbs. She doesn't have a lot of real estate on which to hide a larger gun. She likes her single stack, and she also likes her full-frame G17 she carries when camping. To each their own.