Hi kriss_karnage,
A combination of our genetics and environmental factors pretty much determine what we look like. Regardless of the etiology, however, what can you do about it is a more useful question at this point. Wearing a bra has never been shown to have prevented sagging breasts, so I would not fret over it.
You have somewhat large breasts with your left breast a bit larger. Your nipples are positioned somewhat low on your breasts giving them a downward tilt. And, although you have overall fullness, you lack that in the upper pole.
The good news is that plastic surgery is often available when our genetics and environmental factors failed us. I believe the treatment of choice for you is to undergo a breast lift procedure, the amount of breast volume to be removed to be determined by you and your plastic surgeon. In addition, to achieve long lasting upper pole fullness, an implant should be placed behind the muscle as well. I believe that is the only way to produce upper pole fullness with longevity.
As to the lift that would work best for you, I believe the vertical mammaplasty technique which has a lollipop type of incision without the horizontal is ideal.
I would also urge you to perform this procedure when you are at a stable weight. Any weight fluctuations, either gains or losses, will detract from the stability of your results.
Good luck,
Ary Krau MD FACS