I've never heard of anyone as young taking WU. But let me explain a thing or two. WU contains phytoestrogens, plant estrogens, which are a lot weaker than our own bodies' estrogen. In an adult, they increase the overall hormone actions because they add to our own estrogen's actions. But 14 is the age at which you're supposed to be growing and developing really fast, your hormones are at their highest, so if you take plant hormones now, they may compete with your own hormones, taking their place and actually diuminish the overall hormone actions in your body, thus stunting your growth and development, and not only your breasts, but your whole reproductive system and even your brain. You're not done growing, breasts aren't done developing till 18 in most girls and they still grow till after 20 at many.
PS - For my personal taste, 34B is the perfect size (on a slim body).