First, think of your body as a clock with your belly button 12:00
Your right hip would be 3:00, Middle of your back 6:00, Left hip 9:00.
What you describe that you have been thinking of would be middle of
back. I suggest you forget that because it is an excellent way to get
a serious back injury.
You mentioned appendix. That would be around 1 to 2 o'clock.
This will be controversial I know, but you asked for advice. When you
need your gun, you need it quick. Personally I think pocket carry is
too slow.
In my opinion outside the waistband (OWB) is the quickest, wearing it
at about 4 to 5 o'clock. (Assuming you are right handed)
An open top (no retention straps) is generically referred to as a
speed scabbard. A well made speed scabbard will hold your gun
without retention. It will be much quicker, And you will have it
covered with shirt or jacket so nobody will know you have it.
Then practice a lot, with the gun unloaded. I used to be able to
draw and fire in less than a heartbeat. (About a second) But that
was a long time ago. Now I rely a lot on situational awareness.
Your pistol should conceal well with just an untucked t shirt or shirt.
As far as what holster, I prefer the little revolver rather than pistol,
but if they are made well for revolvers I believe they would also be
well made for pistols, so I will recommend the following. Left to right:
Black Hills high ride. This one is shark, but you can also get cowhide.
Thad Rybka's Gaylord style speed scabbard.
DeSantis Speed Scabbard
Don Hume's JIT
Price Western Leather (PWL) Gaylord style speed scabbard