I performed a consultation for a piercee whose initial jewelry in her nipple piercing was too short:
I got my nipple pierced last night and I think it maybe too small its 14g and 9/16". I am doing the sea salt soaks. Just concerned thats the bar is too small.
The bar is definitely too short for your build! You must visit your piercer ASAP to have it changed for a longer bar. Hopefully the jewelry is internally threaded or the piercer has an insertion taper that will screw onto the existing bar to avoid passing threads through your freshly pierced tissue. See below.
Throughout healing, there should be a millimeter or two of the post showing on each side when your nipple is relaxed out to its widest dimension.
Only after you are fully healed should you consider wearing a bar snug enough that the balls are right up against the tissue.
Here's the information I suggest for aftercare: http://piercingbible.com/piercing-care
Below is a section from The Piercing Bible about embedded jewelry: