I had a breast augmentation done 3 weeks ago, 360cc silicone under the muscle. One breast bigger than other?

There seems to some asymmetry before and after any BA surgery.  I suspect that your right breast had more saggy-ness before surgery, and it is relaxing and adapting to the implant faster. However, if this is a new or acute change, then you should see your PS to make sure that this is not a hematoma.   

Hello, thank you for your question and posting your photo.
It is too early to make absolute comments on your surgery. You are still healing but based on your photos you seem to have some initial asymmetry before augmentation. You had breast ptosis which was concealing this size difference. I recommend you to wait until the end of the healing process and always keep in touch with your PS and listen to his /her recommendations. 
Kind Regards,
Guray Yesiladali

Hi tbh23,

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 3 weeks  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.

Dropping of implants is part of the healing process and this occurs after the tissues surrounding the implants slowly relax, allowing the implants to settle into their final position. It can take about four to six months for the implant to drop down to their final position.

But if you are still concerned, you can always visit your plastic surgeon and discuss your concerns. This way, you will be reassured. Also, if after six months, you are not satisfied with the appearance of your breast, you can visit your plastic surgeon and discuss your concerns.

Lastly, follow your plastic surgeons post-operative instructions and advice for faster healing and recovery.

Daniel Barrett, MD, MHA, MS

Certified, American Board of Plastic Surgery 

Member, Am. Society of Plastic Surgery

You are still too early in the healing process and what you are seeing now is not your final results yet. Swelling typically persist for a few months after surgery. The swelling in each breast differ from the other, thus one breast may be more swollen, in that case, looks bigger, at one time. It would be best to wait for about 6 months when your body fully recovers and follow your surgeon's instructions. By then, when you are fully healed, you may decide whether you are happy with the results or you'd want a revision.

Hello,
I am sorry to say this that I can not find any reasons for you to be unhappy with.Patience is what you need now.
Its going to be a good and a perfect result 6 months form now.
I wish you all the best.