i think the first thing you need to do is go see a doctor get it checked out to see if there is some hormonal deficiency,i doubt it's a hormone deficiency maybe your body didn't go through puberty long enough as I have heard of that.
If that is the case and you have breast tissue there which i'm sure you do then you can always try breast enhancement pills.
I have been doing research on these pills for quite some time now and I have actually just ordered some last week and am waiting to receive them.
There is a forum on this website about this very thing.
There are a few of us that are trying different brands and we are watching each others progress to see which brands really work if any at all.
So go on and read what has been happening and keep checking back as I am going to keep everyone informed on how I go.
I am doing this myself as I used to be a full c cup-small d cup before I had my children but after breastfeeding my breasts have gone down to a b cup so I just want to get them back to what they were.
Look for "natural breast enhancement" on this site and I hope this has been helpful to you.