Abdominal pain 23F 5’3” 140lbs

I am trying to figure out what is causing upper left abdominal pain, here are some of my symptoms: -pain is in upper left abdomen, ranging from under left breast to an inch or two below the rib cage

-some pain also presents on my back, same area, but near my spine (not sure if I described that well)

-pain sometimes also manifests right below my sternum

-was diagnosed with GERD

-lots of belching, when eating and when not

-some symptoms of heartburn

-pain can be dull

-pain can feel like a pressure coming from inside

-pain can also feel like a burning pain

-comes and goes

-can hear and feel gas moving around near that area

-sometimes pain is felt in other parts of my abdomen aswell

-have had chronic constipation for a while now

-under a lot of stress

I genuinely have no idea. I would appreciate any advice or feedback as I have been seeing many doctors for the last year and haven’t gotten anywhere with any diagnosis for these symptoms and other things that I have experienced. Thankyou for you help really appreciate your time.