I'm a doctor- as Bitteroldotter said, the test is whether a competent doctor would have made the correct diagnosis at the time you presented to that doctor, based on the information available to them at the time- or should have been available, had they taken a suitably thorough history and performed appropriate examination and investigation.
If the information was (or should have been) available, and the diagnosis was missed, then missing it was negligent. On the flip side, this means that if a similarly qualified doctor would have followed the same diagnostic steps and treatment options as the doctor in you case, then it will not be deemed negligent- even if there is has been an adverse effect on you.
Note, I said similarly qualified doctor would have managed the case in a similar manner (so for example, a GP would comment on the management of a case by a GP- GPs would not be expected to make a diagnosis that falls into a specialist category, although they wold be expected to refer appropriately). It can get quite complicated.
Also, if by the time you presented, medical intervention would have been unlikely to alter the outcome, then you will also struggle to be compensated.
I can only imagine the terrible impact this has had on you. I can't say, based on the evidence you have given, that this categorically will be a case of medical negligence, but if you feel strongly that you have been treated poorly, then get some advice.