Hiya @nixon,
Some girls are worried about being too big, others are worried about not being big enough,
I think its not as hard of a decision to make once you realize what you would you would be more happier with yourself, on your body, with the sizes lingerie you want to wear as bigger sizes arent always available.
I myself prefered to go for the bigger size rather than the smaller size as i believed i could carry off the bigger size.
What size are you hoping to go for? Implants also measure bigger, but look smaller, i.e i will probably be around a gg/h with my 800s as i was a 36dd before, but i believe i will look around an f/ff and in clothes they look more discuised! 🙂 hope this helps, if you have any further questions i may be able to help and there are girls on here who can sure help also!