Always getting misdiagnosed with appendicitis

It took me 9 years to get my endometriosis (which was 2 years ago). They always found "normal" results on ultrasounds, with maybe a cyst or two that they are never worried about, and diagnose me with acute appendicitis. I ended up in the ER last night for pain and let them know about my endometriosis, and they still diagnosed me with acute appendicitis, with my notes say that my pain was too severe to be consistent with endometriosis. I can't even believe sometimes how invalidating the medical system can be, even after confirmation of the disease. I'm just frustrated.