If you plan on pocket carry its going to matter how much weight and bulk you can put up with, and how easily you can draw it. Hand size and dexterity have a lot to say here. I can wholeheartedly recommend the Truspec 24\7 tactical pants, as I have been wearing them for about 9 years and they seem to last forever. You probably don't want the cotton blend, but the straight up polyester. (I have seen wear in some of our guys that bought the cotton blend.) I have carried a Glock 27 with +2 extension in a Galco Nemesis with no issues, and I have large to X-large hands.
The hard part about this set up is the safety. Most of your lightweight polymer pistols these days don't seem to have them, and those that do are too big for your application. I was looking around and online window shopping and found this:
SIG SAUER P365 9MM 3.1” MANUAL SAFETY PISTOL, BLACK - 365-9-BXR3-MS
If you can stand a P365 sizewise in a pocket, that might work for you. The claim about an inch wide, which isn't too bad for 10 rounds of 9mm, in a +P capable package from a known manufacturer. They are not out just jet, but internet rumors, and we all know how reliable they are, are saying mid Summer.
Slap one of these on it for ~$90.00
TLR-6
I'm partial to meprolight night sights, so lets throw them in here, and figure another $40 for a decent pocket holster, and about twice that for a belt holster of some sort, this comes to mind, although they don't list it for the SIG yet. One of the classics, the Crossbreed can be seen here. The Sneaky Pete line offers a lot of serviceability for $50-70, but you would have some twit asking whats in it. The up side is that it isn't in a pocket or waistband, so its more accessible and more comfortable.
So lets look at our costs
Sig P365ms $500.00
TLR-6 $90.00
Meprolights $83.00
Pocket holster $40.00
Belt holster $75.00
For a grand total of $788.
Of course we haven't discussed ammo and cleaning supplies, but as I recall from other posts, you have an M9, so you'd already be set up for that. Shipping would be extra, of course, so ordering as much of this stuff from the same source would keep that down.