Are my implants too small for it to be 415 cc? Do all implants brand measure the same size implants or are they different?

At three weeks you will still drop and fluff. As the shape improves, you may find quality rules over quantity. You need to allow your breasts to heal, and your skin/muscle to stretch before revision. The volume of your implant is sitting high, because they have not had a chance to settle. When is is time to revise, if 415 is too small 440 will also be too small. Be sure to follow-up with your plastic surgeon.

It is still far too early to determine how the implants will look on you. It takes 3-6 months for breast implants to truly settle into place. During that time, your implants will drop a bit and your skin will stretch to accommodate the larger volume in your breasts. After all of this happens, it is not uncommon for women to say that they feel their implants fit them a bit better. However, if after six months or so you are still unhappy with your size, a simple implant exchange is a very short and easy follow up surgery.

Dear rose098,
I understand your concern and it is quite normal to be concerned about the outcome following a breast augmentation surgery. However, you are still in the very early stages of the healing process at 20 days  post op.Your will need to be patient at this moment and follow what your surgeon has instructed you to do post operatively.At the early stage of the healing process, the tissues around the implants are still swollen. Once the swelling subsides and the implants drop to their final position, you will be able to see the final result of your breast augmentation surgery.
Daniel Barrett, MD