For an easy to conceal pistol, a Para Ordnance Warthog is pretty good. .45 ACP, 3" barrel, OAL 6.5", height 4.75" The capacity is only 10+1, but with the spare magazine, it is 21 total. It is a 1911 clone. They also make a "Hawg 9", but I'm not sure of the capacity.
.45 ACP is not too costly. Some problems with .44 mag for defense against people are that the guns are heavy, bulky, and expensive. They only carry 6 shots, and to use speedloaders requires some big pockets. Also, the recoil causes serious muzzle flip, therefore time to get back on target after every shot. But .45 ACP is a relative pu$$ycat to carry and shoot
Now, if you are concerned about defense against bears, the .44 mag is a viable option.