Quick story to summarize this topic:
I put together an outfit that I must not have used before: dark navy khakis (someone will have to explain how dark navy pants can also be "khaki"), dress shoes, and a quarter-zip sweater. I put on my gun/holster (PX4CC in a JM Wing Claw 2.5), and it stuck out under my sweater like I was pregnant. I thought "What the hell? I wear stuff like this all the time."
The difference was the belt. My "dress belt" for years has been a Daltech Force SuperBio belt, supposedly a "dress gun belt." Yes, it may be a (decent) gun belt, but not for AIWB. In a semi-panic, I switched only the belt to my Graith Specialist, and the gun bulge went away.
This is not an endorsement for any particular product, but just to highlight the importance of your belt choice in making AIWB "work."