Meshaw is likely as it's not that far from East Worlington. I have a Boundy from Meshaw married to a man from West Worlington in 1829. And the name crops up in all 3 parishes.

Are you sure they married? The entry (one line) in the marriage register is crossed through.

Have you looked at Tim Treeby's website:treeby-family.co.uk. He's done a lot of work on the Boundy's in that area, and he solved a brick-wall I had with my Boundy connection.

Do you know when Elizabeth died, to get an idea of her birth year?

There's a gap of 7 years between John and Elizabeth's first child and the next, so if Elizabeth was born around that time, perhaps she was baptised elsewhere (mother's original parish?)