Beachgirl42 on Family Tree Circles

I have a marrige cert. for Ann Caroline Virginia Fuller m. William Willetts in NZ age 17 date 1857. No other information. On her death certifate 1886 it is stated that she was born in Australia to parents William and Elizabeth Mary [no maiden name] and had been in NZ for 38 yrs. I am not entirely convinced that the Ann born 7 8 1840 in Pitt Town NSW is the correct one. Partly because I would have thought all of her names would have been on the birth cert. Could anyone shed any light her please?.
Beachgirl