“queer” as an identity is a way to reject expectations of a unchanging sexual identity. judith butler has written heaps about queer theory but understandable if you don’t want to read her stuff, it’s very convoluted, but basically even people who only have sexual/romantic relationships with people of the same gender can identify as queer if they wish. 

i feel like as i have grown older and changed a lot of my sexual and romantic feelings have changed. when i was trying to sort of figure out who i am, i felt like words like heterosexual or bisexual or pansexual didn’t seem to fit, but i feel way more comfortable identifying as queer, because to me it leaves room for change. of course some people are very comfortable with other identities and having boundaries! it’s just down to the person and how they feel.