Gastroparesis is not fun, but if your stomach emptying test was only 15 minutes off, it seems like your GP was relatively mild. Mine was 18 minutes slow. It helps to eat small frequent meals, low-fat. Cooked veggies are easier to digest than raw.
Gastroparesis can cause stomach pain, bloating and nausea. It does not generally cause gallbladder problems, but you could get a gallbladder test if you get right-side pain after high-fat meals.
You can reassure your children, GP is sometimes nasty, but it's not fatal.
What are your most troublesome symptoms? What kinds of doctors have you seen?