The big variable no one has mentioned is girth. How big a boy are ya? </Roy D. Mercer>
My waist has expanded over the years, but I'm broad shouldered. At 5'10" and 230 pounds, I carry a full size pistol (Ruger P97) in either an OWB slide, or Fobus paddle, with just a XXL shirt covering.
I prefer, and usually wear, a T shirt tucked in, then a Hawaiian or camp shirt over that. The T sure beats gun-on-skin. But, if circumstances require, I can get by with just an untucked XXL T shirt. If I don't have an outer cover garment other than the T shirt, I'm pretty careful not to bend or stretch in a way that stretches my shirt.
The bottom line: no one is going to notice. Most people are oblivious. They're more likely to notice if you're self-conscious about it, because you'll be adjusting and checking yourself constantly.
Just throw something loose on top, relax, and carry!
Kevin