Would 520 cc fit 122 lbs/54kg body frame? (photos)

520cc implants will look like
very large, saggy breasts on your frame and in the skin envelopes of your
breast. This size breast is not
proportionate with your body size, therefore will result in a chest that does
not look natural. Your nipples tend to
point downward, as well. A breast implant
will not change the position of your nipple, in terms of the direction that
they point. Having less volume, but with
a breast lift, would probably be a better alternative for your situation.

You are definitely a candidate for a Breast Lift. Do your research and find a Board Certified Plastic Surgeon who specializes in breast surgery.  Honestly placing implants in your breasts, without a lift would not give you the optimal result.All the best to you. 

Based enthuse photographs your starting point and your desired outcome are inconsistent.  You might benefit from a lift.