What exactly makes breasts tuberous and what are the different types? Can breasts become tuberous over time? (photo)

I've been told my pre-op breasts are somewhat "tuberous" but they don't look like most I've seen. While they are widely spaced with tight creases, they don't have the ptosis/tuberous looking shape I normally see. Why are mine different? I've also heard that tuberous breasts are a genetic thing, but before I lost a lot of weight a few years back my boobs used to be 34DD and weren't constricted then, but after weight loss they never got big again and seem tighter than before. Why could this be?