Based on what is known of Amy Chambers only one baptism was found around the right time.  This also happened to be in Fakenham.
Her parents are given as Richard and Frances Chambers.
Given that the FREEREG records may be imcomplete the identity of Frnces is reasonable.

Searched for marriage of Richard Chambers in Norfolk, 1739±10, one found in Norwich and one in Fakenham to Frances.
The transcription gives her name as Derwent, which is possible, but so is Durrant, which is more likely.
Reasonably certain that this is the correct marriage.

There is a burial for Richard Chambers aged 46 in Fakenham in 1761, this would mean he was born about 1715, which is reasonable.
There is a burial for Frances Chambers aged 71 in Fakenham in 1769 which would mean she was born in about 1698.
If they are husband and wife then she was 17 years older, which is unlikely.  She would have been 42 when first known child born.
But if she was his mother then he was born when she was 17, which is possible.

No conclusive baptism found for Richard or Frances.
Nor any evidence for marriage of Richard's parents around that time if Frances was his mother.
Nor any evidence that Frances remarried after Richard died.