30 is the length around your torso, it doesn't really have to do with boob size. If you have a wider torso, the number will be higher. The actual boob size is the A. You can't really do much about that. There are things that say they will make them bigger, but in all honesty, I have not heard of any single type of product working, nor natural remedy. The only way to actually increase your breast size is by surgery. But if you can't have surgery, many girls buy bras that have a little extra padding, or sometimes a lot of extra padding. It's not stuffing, and not even obvious. I know places like victoria secret sell bras that you insert packs into the actual fabric, no one would even know. Besides that, pushup bras do help.