Ever wonder why some babies seem to nurse constantly while others go longer between feedings?
It all comes down to:

Fatty Tissue: Shown in yellow in diagrams, fatty tissue largely determines the size of your breasts.

Glandular Tissue: The milk-making powerhouse! It resembles tiny bunches of grapes, with each "grape" (alveolus) filling with milk. These contract to send milk through thin ducts to the multiple openings in your nipples.