Carr is a non-Manx name (tho sometimes it is a form of Kerr) - tho it is found on Island from 1800 often in Douglas - from the 1841 census can be Irish, Scots or English.

If the marriage in 1837 was on Island then at age 17 Susan would have needed permission from a parent or guardian who would be named on the marriage cert - also can't see her in the 1841 Manx census - where did you find the marriage