Amniocentesis advice?

J 💗💙👼🏼💙

Had the screening for downs ect at my first scan and it came back low. At my 20 week scan they said that baby has a lemon shaped head and that it was hard to see the cerebellum. I had two scans done and have another one tomorrow at a more specialist hospital and was asked to decide whether I would have the Amniocentesis. Advice from people that have had it? The chance of miscarriage concerns me, any advice appreciated.