I agree with Dr. Feldman's answer, who succinctly described what I feel you will find with these implants--you will have a gaping wide-cleavage unnatural look with globular "Baywatch coconut" breasts that look decidedly "fake." (They won't be too big, which is one definition of "fake," but they will still be terrible-looking!)
150cc will add less than 1 cup size to whatever breast volume you presently have (by your description that is not much), and the extremely narrow base diameter of these HP implants is too narrow even for your petite frame and naturally smaller breasts.
I also wholeheartedly recommend a second or third consultation with other ABPS-certified plastic surgeons who do lots of breast surgery. You should also bring goal photographs (look at the before and after photographs of many of our websites) of breast "looks" that you find attractive, and you should also try on various implant sizes in a bra and stretchy top to see what looks good. Don't even look at the implant sizes until you decide what looks good to you. Then trust your surgeon to add about 10% more than the selected volume to account for the submuscular compression of the implants that make them look "smaller" than your sizing choice. The profile should be based on your breast base measurements (we all do this somewhat differently, since the breast does not have a "sharp" beginning and end), and should be the lowest profile (widest appropriate width) to give you the nicest cleavage. At this small end of the implant size scale, you will require moderate profile implants for the best "fit."
Truly, size choice is critical, since you really only want to do this once! I rarely use implants below 250cc (even in tiny patients such as you who want a "natural look"), and in this small of implant volume would need to use moderate profile to get adequate width to properly fill the breast base and avoid Grand Canyon cleavage. 150cc HP implants are way too narrow, even for you! I think they may be too small as well, but this is only speculation without a physical examination and personal consultation. Many plastic surgeons do this at no charge, as I do.
Surgeons who "always" use HP implants (usually because they say HP gives better upper pole fullness) are NOT selecting implants on the basis of individual patient goals and anatomy, but simply using a "formula" or following a "habit" or routine. NOT GOOD.
HP is not "fake" in and of itself. But HP implants are very narrow, especially the 150cc ones, and you will likely not like the look they provide. Get more opinions in person, please! Best wishes! Dr. Tholen