Doctors are very experienced at physical examination and how different patients will describe pain. Also, blood results will show a pancreatic enzyme marker which will indicate whether it's inflamed.
I went to the GP about 2 two weeks ago and and pain all over my abdomen. On examination (where they lie you down and poke and prod), I had upper abdominal pain, whereas where I was experiencing the pain all over.
A urine test showed blood in my urine and a slightly elevated white blood cell count.
All in all, she started me on antibiotics for a UTI but said she wasn't fully convinced that that was the whole of the story so referred me to A&E.
In A&E, they immediately suspected pancreatitis (pain penetrating just under left breast to back). Took bloods, and pancreatitis was confirmed.
I'd try to trust the doctors. To be a GP, she/he will have had at a minimum 10 years of study. Plus whatever actual experience she/he has. Examination of a patient is something they're quite good at, as it's really really not in their best interests to miss something.
Try to relax. Blood results and physical examination can reveal a lot more than you might think.
Hope you get better soon.