Cuban and American are nationalities not ethnicities, do you know your father's ancestry? maybe he was of mostly european ancestry himself it's not uncommon, if he was and your mother is of full european ancestry then your non european ancestry must be very small, so it will not show so much in your looks i think.

I think that if you look white, and people think you're white, then you are, you may not be "pure" but who cares, if you see an option of "race/ethnicity" on a test then put your white.

also Hispanic is more of a culture rather than an ethnicity, and latino/a is more like a term used in the US, at least in my country many people do not use it.

"White" is a weird ambiguous term too, are all europeans white or just anglosaxons? are slavs and mediterraneans white?