I'm a total hourglass. My bust and hips are the exact same measurement, and my waist is 12 inches smaller. Even at my high weight I still maintained that general shape, though the ratio was less pronounced. For the record, shoulder width and hip width is a bit more accurate for diagnosing body shape than bust size. There are some true hourglasses with fairly small busts, but their shoulder width and rib cage is equally wide as their hips, with a pronounced waist nip. Not all hourglasses are equally voluptuous at any size
Most women I see are slightly pear-shaped, or rectangles/rulers, but there are definite hourglasses at all weights. There are some more complicated systems of body shapes where there are eight to ten body shapes instead of three or four, and that tends to be more accurate.