a lot of heterosexual people's attraction seems to be contingent on conformity to gender norms, as much or more than it is to good-looking bodies of the opposite sex. We "perform" gender in large part to attract others, who are conditioned to respond to it.
As an old woman who has seen some shit and even learned a bit from it, it's not that linear.
The genderised dressing signals the sex, yes. And when you first see someone of the opposite sex wearing something you have gendered expectations of, whether it's a trans/gnc¹ person of your own culture or a person from a culture where that thing has a different gendered code, you initially read some element of the opposite sex.
However, over time, as you become accustomed to seeing it on the opposite sex as well, your original gendered expectations weaken and you just read the sex of the person.
So while I agree that in the moment, there's an element of gender presentation in sexual attraction, the underlying driver is the sex not the gender.
(Oh and BTW plenty of straight women find feminine coded men attractive so it's definitely not because you are "bisexual and the very unconventional"!)
¹ GNC standing for both Gender Non Conforming and Gender Not Caring 😁