Like HH said earlier,, it's amazing how under the radar breasts are. I used to worry but soon realised that no one notices or cares.
Best stealth bras are the seamless bralette ones as these usually have wider straps, no buckle/fasteners, no wiring and being seamless are thin.
It's what I wear, and even under a tight form-fitting tee, no one has said anything, not even my close family.