Muggle,
Since you are European, what kind of solution is in your band? If it is not saline, there is a chance that the solution is the kind which draws Water to itself, which would account for it "self tightening" after awhile. Since the band is "semi-permiable" Fluid will move in and out of the band itself. I would have that checked, and have only saline put in from now on. I've heard that European docs sometimes use this other fluid.
Also, as to the port location, I would be asking the new surgeon that you are preparing to see about moving it. You should not be in such discomfort because of the port.
Tamster