Implants can change throughout you life time. After four months any changes will be gradual unless a major event like pregnancy occurs.
Wait at least 6 months for revision implant surgery if possible
This is especially true when there was pre-existing asymmetry. The changes will happen more slowly, but the best advice is to wait 6-12 months unless the problem is severe.
Thank you for your question.
Although a picture will be very helpful to see, the answer is that you can replace the implants at this point as long as your lab results state that you're in a healthy stage to have another surgical procedure.
Yes, your breast will continue to change
Your body is not made of stone and is constantly changing. Your breasts will continue to change a little over time. Waiting a year is not a bad plan