Hello Helen,
I did a search for Betty on Freereg but couldn't get her baptism. I suspect that the baptisms for Publow haven't been transcribed for the period in question. There were very few entries indeed. There are some clues in relation to the marriage of Charles Flower and Betty however. I note the marriage was By Licence, this suggests they were of some standing. Also, Charles Flower is shown as of Long Ashton parish.
Freereg has a marriage in Publow on 24/12/1784, William Holvey to Flower Ashton.
There are a few couples by the name of Holvey, Holvy etc baptising children in Publow in the 1780s, 1790s and 1800s. These were: William and Flower Holvey, James and Mary Holvy and John and Hannah Holvey. Both James and Mary and John and Hannah baptised children in Pensford.
There is a burial for James Holvey in Publow in 1840, he was aged 74. Mary Holvey, possibly his wife, was buried there in 1833, she was aged 68.
I think Betty Flower was buried in Pensford on 06/03/1834, aged 93. The Freereg entry shows her abode as Publow. That puts her year of birth as c1751. It is open to speculation as to whether she was the same Betty who married Charles Flower.
There is a burial for a Charles Flower in Pensford on 12/09/1812, he is shown as aged 85. That doesn't match with the baptism you have found.
The Publow PR transrciptions are on the Somerset OPC database:
http://wsom-opc.org.uk/index.php?id=39&k=465I cannot find a baptism for a Betty Holvey. I suspect that William, James and John may have been related to her however.
Jo.