I as a man can only be heterosexual if I exclusively am attracted to women.
"homo-" means same or similar.
"hetero-" means different or other.
i am not usually the kind who immediately cites definitions of words, however in this case, this is how the prefix is used and understood all over the scientific world https://www.etymonline.com/word/hetero-
your definition of heterosexuality is very unusual to me and as a bisexual nonbinary woman, it definitely does not fit for me.
im curious tho, do heterosexual nonbinary ppl exist in your definition here? or is that mutually exclusive?
and whats the equivalent of nonbinary ppl who arent attracted to other ppl of their own gender but only those of a different gender?
lastly,
And enbies are not women, even if AFAB. They are neither man nor woman, that's what makes them non-binary, that's the point.
nonbinary men and women exist and are valid gender identities.