Revision of breast reconstruction - how much bigger could I go?

Two ways to increased size after an implant- based breast reconstruction are to undergo implant exchange for large implants, or add fat transfer for natural volume.
In cases where there is significant assymetry, particularly in shape rather than just size, fat transfer can be helpful. Fat transfer would be removed using liposuction from a stubborn area of the body and transferred to the breast.
In cases where radiation was required, the cancer side often develops some degree of capsular contracture, which can also be release to improve shape and symmetry.

Thank you for your question.
Without photos or a proper evaluation, it is difficult to say what your options are. I recommend meeting with your reconstructive surgeon to discuss your options moving forwards. They should have a full view of your treatment and past surgical history to assist you in making the best decision.