Breast Implant Size Advice for a Conservative Look?

Breast implant size is very personal and is dictated by your size, weight, current breast tissue, current breast size and your desired outcome. Discuss with your surgeon what you are expecting from your surgery and ask to see pictures of people who are your size. Bring pictures with you of what you would like your breasts to look like so you and your surgeon can be on the same page about size, placement and profile.

This is a tough question to answer without the benefit of a physical examination.
By 'conservative', I'm assuming you mean a very natural, and perhaps even an 'unaugmented' look- when wearing clothing, an observer might not even consider that you've had a breast augmentation.
To achieve this look, I think its important that the implant 'fits' you well. Each implant has a specific base diameter relative to its fill volume. If this base diameter is wider than the footprint of your breast, then the resulting augmentation will not look 'natural'. The wider implant will change the shape of your breast, and that is not what you want. In my opinion, a conservative breast augmentation preserves the shape of your existing breast tissue, but adds to the projection of your breast mound.
Your best bet is to find a plastic surgeon that has done some natural looking augmentations (look at the before and after photos on his/her website), and schedule a consultation.
Scott Sattler MD FACS