“We aren’t talking African American or Caribbean American here and if those were on the CA as ethnicity, it would be open to debate.”
The question the OP asks about is how to define oneself within the rather murky definition of ancestor, and within the less murky, closed set of characteristics used to define Hispanic. There are issues of a challenge to OP’s identity integrity being considered.
It can be inferred from the mention of the color of the eyes and hair, and skin, that OP is concerned that others perceive that OP rests not within the easy definition of Hispanic, but with the Caucasian Non-Hispanic majority here in the U.S., and is the recipient of the privileges that come with such a designation.
As such, in this secondary component of the OP’s concerns, I discussed a issue parallel to the OP’s which my son will face over his lifetime. No one has confused or thinly extrapolate the issue of race with that of ethnicity, the OP’s chief concern.
(Note: In a close re-read, OP never explicitly states that she holds herself to be Hispanic, nor that she has claimed it throughout her lifetime, but that her mother has so designated her.)