Good job knowing your own body and advocating for care. Doctors are far too quick to slap a dismissive diagnosis on something and stop looking for deeper answers. "It's because you're too fat" is one of their favorites. When I had metabolic syndrome I tried and tried explaining that my cholesterol and blood pressure readings went crazy, then I put on all this weight. All they saw was an overweight woman with conditions made worse by weight. They uniformly said if I lost weight the other things would improve. It took a lot of self-advocacy and research to find a doctor who realized the root cause was food sensitivities, causing inflammation, causing everything else.
Stay strong and good luck with your surgery and treatment!