I just recently obtained my CHL as well, and I can attest to so many of the things that folks have previously talked about. I also live in Texas, so the heat is such a factor in how you carry.
The "fidgiting with the shirt", the constant feeling that someone knows, the weird feeling that you are doing something wrong, etc... goes away with consistent carry. My trick was to force myself to "forget" I was carrying. It worked...would make me feel more comfortable.
What works for me...
I occasionally pocket carry. The holster has to be good, BUT the pocket has to be big enough or the gun will print like crazy. I've looked in the mirror and just laughed when wearing certain shorts.
I bought a few cheap holsters to try out where I would like to carry IWB. After much experimentation, it became apparent that for me the 10 o'clock cross draw with a "Sticky" holster ended up working the best. My primary carry is a Kahr CM9, and it absolutely disappears, is very light and comfortable, I can sit in the car, and it is pretty damn fast to present. Even when hugging someone they don't know it is there unless you are full body pressing them.
What is also cool about the Sticky (or Remora/Stays-Put) type holster is that you can adjust it easily for the situation, and it stays right where you want it.
Closer to your carry gun needs, I also carry my SIG P245 45auto which is a little closer in size to your HK. I was very surprised that it disappeared with a Sticky almost as easily as the little Kahr did. I actually walked in the living room one night after the holster arrived and asked my wife to tell me where it was. She thought I was trying to trick her by not having one at all, and was doubly surprised when I showed her that not only was I carrying, but it was the bigger SIG.
The Sticky-type holsters are not that expensive either, so they are easy to try out. Anyway, good luck, and let us know what you end up sticking with.