Maria, I hope you can get a proper diagnosis soon! I know what it if feels like to be searching for your own answers. I did that for years, too. It's difficult, we think we might be crazy sometimes when doctors tell us apparently there is not a physical problem causing the symptoms we experience.
I have had a hiatal hernia for many, many years - it always showed up on endoscopy and chest ct scans. I wonder if you have one of those sliding types that go up and back again. Also, many people have hiatal hernias that never experience any type of issues related to it.
I have another comment, though. Many times, adults that normally eat all types of foods are fine, then they start experiencing trouble that gets worse over time. It turns out they have gained an intolerance to a certain type of food. For me, it is corn - all forms of it, high fructose corn syrup is my enemy. For others it might be dairy products. For some it might be gluten.
While you are advocating for yourself with getting a proper diagnosis, you could try an elimination type diet. I don't have a link to one, but possibly someone else on this site could help with that.
Good luck! Take care and keep pushing for the proper diagnosis.