I have endo and based on all the endo forums I frequent, there seems to be a lot of anecdotal evidence that women do get fobbed off for many years. I personally started going to GPs 10 years ago and was told it was IBS, just part of being a woman, it would stop in my 30s etc (it didn't - it got worse) They did ultrasounds etc but I know now that ultrasounds don't diagnose it. Eventually one female finally GP suggested endo, but told me it would be a 5 month wait to see a specialist, then another 5 month wait for any diagnostic surgery. I love the NHS but did feel a bit let down at that point, especially after miscarriages and a couple of years trying to conceive
Then I moved abroad, and achieved a) a referral to a specialist, b) diagnosis and surgery for removal of endo and c) pregnancy all in the space of 2 months!
It's hard to blame GPs exclusively though, there are clearly bigger issues around awareness and fundraising. Even my mum used to think I was a wimp for wanting to be off work during a period, and told me to get over myself. I doubted myself and started to think I wasn't as 'strong' as other women!
With surgery being the only way to diagnose it's natural that the NHS would want to explore other options first I guess, but with me when other problems were not found they just never took it any further, so I suffered for 10 years. Maybe I should have pushed harder, idk. But I feel so sorry for women who suffer constant debilitating pain, or who may want kids but not be able to - it can be a desperately awful and lonely disease.