You have some form of scar contracture, of which capsular contracture is possibly a part of. Your periareolar incision put you at higher risk for this phenomenon; dissection of the breast tissue creates injury that scars internally, causing possible deformities like scar tethering, something you may have. This is an under reported problem with the periareolar incision. Most surgeons are just now acknowledging the increased risk of capsular contracture with periareolar incisions though.
You will need to be examined to determine what would be appropriate for you. If you do opt for a revision surgery, I highly recommend you don't reuse your periareolar incision, but instead go through the inframammary crease.
Best of luck!
Different shape breasts
The changing shape of your breast may mean that there is more scar tissue around one of the implants than the other. This is a common occurrence. However, from your photos, they look very good.
Changes in Breast Shape: Rule out Capsular Contracture
The most common reason for changes in breast shape this long after surgery is capsular contracture. If you look at your first photo and the last, it appears that your left breast crease has elevated to some extent. This may represent a minor capsular contracture. It may also be that your left crease was higher than your right before surgery. A preop photo would be helpful. However, to rule out capsular contracture, I would see your doctor to evaluate the breast. There are several medications which may be useful to assist if early capsular contracture is forming. Also, ask you doctor about breast massage which may help. Best wishes!
You may have a small seroma in the right breast which is making it larger; A screening ultrasound should clarify your concerns.
Asymmetry after breast implants
Thank you for your question and photographs. A "before" picture would be really helpful, too, to answer this question. You have an excellent result with your breast implants. No two breasts are alike, and there is some aspect of asymmetry present in ever patient. Before augmentation, when your breasts are smaller, the asymmetry is not so noticeable; but when implants are placed, the asymmetry becomes exaggerated. I believe this is what may be happening in your case. Your chest wall and breasts are not identical, and therefore the implant sits differently along the chest wall. Regardless of this, you have an excellent result. Best of luck!