can easily be 'overfilled' but as Dr. Thomassen notes, the implants to replace the expander don't go over 800 cc's so when you consider the fill and the size of your port, you're nearly there and really don't need anymore filling. If you have access to custom implants that will exceed 800 cc's, then you can continue to expand.
I have specialized in XL breast implants for many years. I have a special arrangement with a couple of breast tissue expander companies as well as custom XL silicone manufacturer and have offices in California/Miami/Nassau/ANGUILLA AND ITALY. Some of my patients have gone well beyond the size that you wish to be! I woiuld suggest you visit my website specifically for XL patients below.I am available for FACETIME/SKYPE/Whatsup video consultations.