What ever size fits is the right size bra. Age is not a factor. If you're 6 foot or close to it well 36D wouldn't look so large. However if you're closer to 5 foot it would look larger. Proportion is more of factor with how things appear on your body.
If you're fat and ugly, no one cares.
Is that Big? Yes. Is that Bad? No.
No, that's not bad. Most consider that a good size.
NOT BAD AT ALL...some guys (including me) like them "big".