Questioning how sexuality "works"

Hi people ^^

So here's the thing. Im a transgirl and im sexually attracted to girls, but im still confused.. btw what i'll say may be based in transphobia, im so sorry in advance TvT im still learning about it

What im saying is i love women a lott~ but when it comes to sexuality i dont really consider the genitals usually. So basically so far i thought i was a lesbian, cause i am very attracted to the female genitalia. However... i did love seeing nudes from a trans girl, with a male genitalia ; yet i dont mind seeing a transman's vagina.

So, im confused. Why do i not like penises on men? How can my brain know the difference between a boy and a trans girl from a photo without context?

I have a hypothesis, which would be i am bisexual and homoromantic, (maybe invented that term there) but im really not sure.