If you will consider .40 caliber polymer...
Given your mode of dress, it appears that you want something pretty compact for easy concealment on your belt under a T shirt or similar shirt worn untucked. And you seem willing to consider a compact .40 caliber gun as well as .45.
I think an advantage of the .40 might be that it gives you larger magazine capacity in general, and probably has just as much effect on a target as the .45. And I personally believe the recoil is not that different than a .45 in a similar gun, especially if you are using the lighter, faster .45 ammo such as 185 grain products.
So I have two suggestions for you in compact, polymer frame .40 caliber guns. The first is the H&K P2000sk model, which has a 3.27 inch barrel, a 9 round magazine, and weighs 24 ounces empty. I have the very similar USP 40c model, and it is an easy gun to shoot which never fails to fire. The P2000sk is slightly smaller and trimmer than the USP, and more easily concealed.
My other suggestion is the similar S&W M&P compact in .40, which is a new gun that has received excellent reviews. This gun has a 3.5 inch barrel, a 10 round magazine, and weighs 24 ounces.