Is 650cc too big for my build?! I am 5’5 1/2, I weigh 155lbs. (Photo)

Dear svamThank you for your question and photo!  Generally for good long term outcomes the breast implant should have a width that is within the diameter of your breast.  Your shape is good - so the chosen implant will give you nice results.With Warm RegardsTrevor M Born MD

Hello and thank you for your question. You are a great candidate
for a breast augmentation.  650cc is a large implant. 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.  This entire surgery
can be performed with a small incision technique.  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. FACS
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.The key to obtaining a natural result is to stay within the parameters defined by your BWD. This will ensure that you avoid the dreaded "fake" look. 
The question of "too big" or "large enough" is a relative question. The safest approach is to stay within the boundaries of your BWD. Beyond that, the choice is yours. Without measures, it is difficult to offer more concrete advice than that. 
Based on your photos alone, 650 cc would seem to be large for your frame. At 5'5" and 155 lbs a larger implant is less likely to yield a "natural" result. The best advice is to use your BWD as a starting point of reference. For more volume and less subtlety at a given width a HP device is an option.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).