Talk to the good folks at PP some more. At this point, they should have enough pearls in their vault be able to match at least another pearl or two to the bracelet for you.
And I agree that "tip to tip" is not an accurate measure of length. It should be the actual length of the bracelet when worn.
Also, keep in mind that pearls take up room because of their diameter, so your "wrist size" in a pearl bracelet is really where the center hole in the pearls is, and not the circumference of your wrist, which will be several mm away from your skin. Bigger pearls require a longer bracelet to fit your wrist.