Some carry a glock 26/27 in an ankle rig, personally I think it's a little large for an ankle gun. Your best bet is what your doing and sticking to a pocket pistol. You can always get a lockbox for your car and keep a full size in there. As far as tuckable holsters for work attire, I don't know about some of you but my business attire allows no room for a IWB holster without being extremely noticeable. You cant really go up in size in dress slacks to accommodate an IWB holster like you can with jeans without looking sloppy and unprofessional, same goes for the shirt. There's a reason people get dress slacks and shirts tailored and not their jeans, there supposed to fit snug.
I have tried an ankle holster. It always ended up resting on my shoe. I guess I have skinny calves and/or ankles. Or a lousy holster.
Find one with a retention strap, this will hold it in place and prevent it from sliding down and resting on your shoe. The Galco Ankle Glove is one of the better ankle rigs out there and has the option of the retention strap. That actually looks to be a glock 26/27 in the photo.