The only other Barrett listed in the index to "Spurriers in America" is Amy's father.She was "dau [of] Thomas and Margaret, Quakers of Virginia."
A standard resource for Quakers who passed thru Va. is "Hopewell Friends History, 1734-1934, Frederick County, Virginia."That book's index has 50-60 entries for the Barrett family, including Amy, but no Spurriers.You may want to look also at the Virginia volume of Hinshaw's "Encyclopedia of American Quaker Genealogy."Beyond that, I think you may be pursuing a blind trail.
Quakers in that era were so strict that marriage to a non-Quaker earned one areprimand, if not outright dismissal from one's Meeting. The Spurriers were seldom if ever Friends, to my knowledge, so a Barrett marriage to one of them would show up indirectly in the form of a recorded reprimand or dismissal in the Meeting records.