I needed well more than 7 cc to feel restriction. That said, even before I did, I acted as though I had restriction and followed my doctor's required eating regimen. Much of my loss occurred before I had restriction, but was due to ---yes!--eating less and exercising more.
I didn't say, "Why have a band, then?" I realized that in order to lose weight I had to eat less. Whether I was banded or not. Once restriction is achieved, it's easier to lose weight, because hunger is not as big a part of the equation. But I still had to eat less, and the band doesn't do that for me.If I choose the right foods, I am now limited in how much I require to not be hungry (note: I did not say "full.").
But "eat less" is not overly simplistic. It is simply the way it is. And if you don't accept that, you will not have the success you hope for.
4 fills, to 7 cc in 2 years---is not adequate. If your doctor is reluctant to fill, I'd look for another. Even small fractions of a cc of saline can have a huge difference. Work hard to get the benefit the band offers--it makes a huge, huge difference.