From your account the ultrasound says the Gallbladder is clear. My understanding is Ultrasounds cover basically all conditions that gallbladder can have except for one, and that is soft pliable Gallstones that have no reflective qualities for the US to pick up. I wouldn't start thinking gallbladder surgery until I've checked everything out further, it could still be something else. Your doctor will have to help you there. Also keep the flushes going trust yourself on how often.
For the acid reflux/ indigestion, have you tried "Slippery Elm" as a herb product. It is very good at easing the problem some people combine this with Aloe Vera.