I am a 30A, possibly a 32A but real small! My question is, will 340cc to 360cc really bring me to a full B possibly a small C? (

Thank-you for your photo and question.
Choosing the correct breast implants may seem overwhelming due to the options available for implant material (silicone or saline), placement (under or over the muscle), implant size and shape. Based on your photo, you would do well with breast augmentation with a silicone gel implant placed under the muscle dual plane. Treatment plans are individualized for each patient based on findings during the consultation to meet your goals. 
Selecting the correct implant size and shape is among the most important decisions in a successful breast augmentation procedure. Placement of the identical implant will not produce the same results in all patients due to differences in:
1.Dimensions of the breast 2.Diameter of the chest 3.Volume of breast tissue 4. Height and weight 5. Breast shape, including breast ptosis and asymmetry
I rely on 3 methods to advise my patients:
1. Dimensional planning 2. Gel implant sizing 3. 3-Dimensional Vectra imageing system.
At the time of consultation, measurements are taken allowing for dimensional planning to select the implant which best fits the base diameter of the breast. Gel implant sizing is performed to allow you to visualize augmentation the with the various sized implants. Vectra 3-D imaging has been a very important method in my practice in selecting the correct implant size and shape as it allows you to see what you will look like following augmentation with any of the available implants. I would recommend a consultation with a Board Certified Plastic Surgeon
Best regards, Andrew Lyos MD, FAC

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  340-360cc may accomplish your goals, but it will depend on your individual breast measurements.  The size, profile, and shape of
the implant is based on your desired breast size/shape, your chest wall
measurements, and soft tissue quality.  This decision should
be based on a detailed discussion with equal input from both you
and your surgeon.   Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most
important aspect is to find a surgeon you are comfortable with. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon

Patients often think in terms of cup size when considering
augmentation. Unfortunately, devices are sized in terms of milliliters (cc) of
volume. This can lead to some confusion when sizing. Additionally, it is
important to remember that cup size itself is not standardized with variations
from one manufacturer to another. Unfortunately, as many women can attest their
cup size in an industry leader such as VS is not necessarily transferable to
another brand.
Another point which is often under appreciated is that of
anatomy and starting point. Any implant will add volume to the volume which is
already present. The implant is additive. A particular volume will not
necessarily confer the same cup size to different patients (often times it will
not even confer the same cup size to different breasts in the same
individual...remember they are "sisters" not
"twins"). 
A general rule of thumb is that 125cc can represent somewhere
between 1/2 to a full cup size increase. Smaller volume differentials (25-50cc)
are typically less consequential representing a volume change of less than
a shot glass. However, I have found these numbers, at least anecdotally, to be
of little help. Patients often present with notions/goals which do not
correlate with these sorts of sterile volumetric assessments.
When sizing patients, there are a number of useful tools
including:
-3D imaging (has the added benefit of offering a volumetric
analysis of the pre-operative breast)
-Breast sizers (rice bags)
-Goal photos
I also recommend that patients commit to a particular look
rather than a cup size. Once a patient settles on a look that pleases them the
overall cup size increase becomes less relevant.With regards to your particular question, it is impossible to say with any certainty what cup size a particular volume will correlate to. One option is to choose a bra/support garment that you are hoping to fill out. Conduct a trial sizing using this bra. While it is not a guarantee of size it will offer some perspective. The best advice that can be offerred is to disregard cup size and instead focus on the look that pleases you. 
As always, discuss your concerns with a board certified plastic surgeon (ABPS).