I’m 5 1/2 ft. 125lbs, is 485cc moderate implant to big? Should I do 445cc? Or HP would be better than moderate ?

When choosing an implant, I encourage my patients to not get too focused on the style or the exact size.  Often the difference in style is only millimeters and volumes changes of less than 50ccs do not often make a significant difference.  I think it is best to focus on an aesthetic result that you like using pictures or 3D imaging, use sizers to establish a range of implants, and then to trust your surgeon to use the best implant during surgery to achieve your desired result.   

Thank you for your question.  I typically prefer the moderate profile implants as I do think that the high profile do look more torpedo like and offer less cleavage.  That being said, with a 445 cc or larger implant I suspect that you will have a very significant amount of cleavage regardless of profile.  Keep in mind that this is a rather large implant for such a petite person.I wish you the best of luck.

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. 
With regards to your specific question, "too big" is a relative question. The best advice is to respect your BWD. What may seem "too big" to one may not to another. It is important to remember small girls rarely have large breasts. Oversizing can lead to a mismatch of frame which is often a hallmark of augmentation and the opposite of "natural." Without measures, it is difficult to say for certain. I recommend that patients first commit to a profile moderate (subtle) vs. high (dramatic). This will then determine the volume range to be considered. 40 cc is a very small volume differential (approximately equivalent to a shot glass) and unlikely to make a huge difference in outcome (within the same profile). High vs. moderate is likely to be much more consequential.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).