R.Y.
Breast size does not correlate with the ability to breast feed. Some people grow more than others but most women can produce milk and breastfeed. I was only a B cup before my first child and only increased maybe half a cup size. I am pregnant now and in my last week and I still fit in my bras that I bought after baby #1.
Since you have a little time find a local La Leche League meeting and go before you have the baby...then you will at least know who to call if you have probems or questions later. Even if you don't go along with everything they are in favor of it is still a great place for reliable BF advise and emotional support.