all i would really say is, dont worry about what ghastly things a non vegan diet has done to your body and embrace the new diet with an open mind. i felt incredibly weird when i first went vegan- partially all the fibre messing with my tummy and also i think because i was incredibly aprehensive...but you get sooo used to it and now i would never ever have it any other way. No matter what you change your diet to your body will need to adjust- boobs and all.
funnilly enough my boobs vary sooo much according to how much ive eaten from one day to the next..minds of their own! i find it fascinating rather than discouraging!
good luck my dear! welcome to this wonderful world!