I've carried concealed (overseas) for some time, on and off, and here is my modest experience:
1) Weight matters, a lot
2) Size doesn't
3) You will forget you are carrying and you will treat the gun like a cellphone or notebook and you will do dumb things (see #4 for some examples)
4) Driving a car is a problem, the gun is always on the way or unreachable, if you put it on the side seat never stays on the same place or worst,somebody can grab it. If you put it between your legs sooner or later you will forget you have it there and when you step out of the car, it will go flying away just like the cellphones. Don't put it in the glove compartment! if you need to show your insurance or other document to the police and reach for it (the document, not the pistol) in the glove compartment, they will shoot first and ask later.
I've carried a Smith Wesson N frame 357 with a 4" barrel, a Taurus PT-92 and even a Ruger single six with a 6" barrel when I had nothing else; nobody ever noticed I was carrying as long they were not expecting it.