HI Jillaine, before delving into pre-1500 sources, it might be better to start with some later generations of the family.
There are two brothers who are both stated to have emigrated to the United States James Nicholas Miles, and Francis Miles, but neither have sources or appropriate pre-1700 sources. James Miles the son of Francis, does have sources mentioned, but no inline citations, so it's difficult to know what source supports which fact.
Perhaps adding sources/citations to these three profiles first, might be a better way of trying to identify whether the earlier generations are likely to be correct, and where they might have originated. At the moment they seem to wander from Southampton, Hampshire, to Radnorshire, Wales and back again.
James Miles appears to be a member of the Society of Friends, and that might be another avenue of research.