ASD is a medically defined disorder. And diagnosis or exclusion of medical conditions is done by medical staff. Information from parents, bus drivers and teachers is useful in working out what is (or isn't) wrong. Conflicting, confusing, or incomplete information should be balanced, interpreted and explored further. Not simply accepted without question.
Doctors should not (and may not) delegate their duty to make accurate diagnoses to bus drivers teachers or any other community members. Delegating parts or all of the diagnostic process to junior doctors, clinical psychologists, specialised SLTs, extended role nurses and other health professionals is usually appropriate, and often helpful. It's ok to worry about misdiagnosing a dc if no-one but mum has ever detected an issue. But not diagnosing when teacher says 'no issues', but ADOS / parents / bus driver etc disagree
.
A private diagnosis probably isn't the way forward just yet. But a detailed check-up by an ASD-experienced OT or SLT (including careful observation in and out of school- ask the NHS first, but anticipate that you'll need to arrange and pay for it yourself) will help.
The NHS paed needs more info so they can work out for themselves if
a) you're causing/ imagining/ triggering ASD-like symptoms
b) SENCO is failing to notice/report (perhaps subtle) signs of ASD issues
c) you and SENCO are both right, so he needs referral to an NHS team specialising in tricky, high functioning dc, to get a clearer picture.