I'd second consideration of a belly band. Try it with your 642. It may solve the problem. Another option are the T-shirt holsters some outfits offer...such as Kramer. Take a look at one on the Kramer website.
If you really want a new pistol, though, and want a .380, I can recommend the Glock 42. It's slim, light, compact, accurate and easy (even fun) to shoot. It's slightly lighter, even loaded, then your 642, and flatter. It may be too large for pocket carry, but would work well in an inside the waistband holster...or ankle holster...or belly band/T shirt holster.
Now, though I like both the 642 and 42, I'd rather reach for a 9mm Glock 26 or .40 Glock 27 if my life depended on it. That may be too big for your specialized circumstances, but perhaps give it some thought if the belly band/T shirt holster solution appeals. Those are more capable weapons, frankly, if you ever actually need the gun to protect yourself with.
I read somewhere that Elvis performed with a weapon on him...a small auto, if I recall correctly...so you are in good company!
Break a leg...and stay safe.