I agree with most of the posts. At 4 months, if you have not seen much change, it is highly unlikely that you will. A capsulotomy and lowering of the implants should resolve most of your issues. Be sure to discuss this with your surgeon on your follow up visit. If the capsule...
Other than the risk of getting a headache from caffeine withdrawal on the day of surgery, I know of no other reason for you to avoid caffeine preoperatively.
400cc should not be a problem and is probably not too big but there are other issues that need to be accounted for when planning your surgery. Getting implants that are slightly smaller in diameter than your breast base width is as important as picking a volume size of implant. Specific issues...