Hi Debbie,
If the dates are correct then the calling of banns was put in place before she was even buried, possibly on the day she died.
The speed of the marriage probably accounted for them going to Bristol to tie the knot. In which case, I expect the witnesses were unknown to the couple.
Genealogy is full of surprises.
Elizabeth
I have just read your last post and with the aid of a calendar, that occurred to me but I wasn't sure if it had to be 21 days or 3 Sundays. It is still very close though.