It may be that you're band isn't well-adjusted right now. An amount of saline that works one time may be insufficient or too much another time. I understand how frustrating it must be to have so much difficulty getting to a good point. I wonder, though, if you're watching for the wrong thing.
Like many, you're talking about "restriction." That's leaving it all up to the band, which isn't what the procedure really is about, not in its entirety. For now, try to forget about restriction and watch for satiety. Over the next week, see what happens when you're eating. Rather than expecting to feel that you'll puke or explode if you take another bite, see if you reach a point where you think you might eat another bite or two, but also feel satiety: "Eureka!, I feel satisfied; I can easily skip those extra bites. I don't need them."
It works for me -- when I'm mindful. I learned at the start that the band is a tool, a partner, meaning that I have a role in events.
From what you've described, you probably don't have a band leak, but I'm no expert. The way to be sure is to ask the adjuster to check next time you go in. The last amount of saline in your band is on record. The NP or whomever withdraws all flud and see whether it's the amount recorded from the previous adjustment.
P.S. WOops I forgot: If you take my suggestion and you truly don't find a difference, make an appt.
