Is there a reason why the doctor had recommended it? Usually it may be because there are some risk factors, such as mum’s age, mum’s health, or complications in prior pregnancies (if any). Amniocentesis has a small risk of miscarriage (0.5%) so it’s a bit unlikely that a doctor in the public healthcare system would recommend it without reason. Might be worthwhile to understand why!
An amniocentesis is a diagnostic tool - higher in accuracy. NIPT is a screening process - can only give a risk profile but if you find out that risk is high, likely still have to proceed with CVS or amniocentesis for a diagnosis thereafter.