Dear Isaac Tate,
That is just a really difficult question for us...strangers here on the net... however, here are some thoughts that come to mind for you, and that is, first, to make sure you have more than one medical opinion? A consultation with another medical team...perhaps even see about a referral to the Mayo Clinic, for example?
Second, to retake that test for FM, perhaps at a different time of day, or under different conditions to make sure the result is replicable? If so, yes I really do sympathize with your family, to take that 19/20 result as basically positive for FM.
Then, consider also consulting practitioners of alternative medicine; naturopathic, even Traditional Chinese Medicine if that is in your locale, and see what they say for you.
Meanwhile, do stay on the very best nutrition you can. When I helped my brother with acid reflux, he was able to control it completely through diet, but I don't have experience with gastritis and FM.
My experience with my own health problems has been just to gather all the information, and find your way through step-by-step. Also, keep your motivation high, for the sake of your family if nothing else; stay alert to learn lots, and do whatever is needed for the best quality of life.
My heart is with you, I do wish you the very best.