If you want a G19’ish type gun, take a look at a G48 with shield arms mags. It’s the slimline version of a g19 that holds 10 rounds from Glock but 15 with shield mags. Essentially giving up nothing to the 19 except girth.
I am not skinny but am tall. The G48 hides well under just t-shirt, especially if it’s not skin tight. I really like the concealment express/rounded line of holsters. The biggest addition to making it conceal well if you are skinny and want to hide it under a t shirt is the claw. It tucks it into your side tight. It is slightly less comfortable with the claw (it’s removable) but it is probably worth it. As always, a good belt is paramount.
