Just trying to clarify the difference between ace/demi and choosing not to have sex/not wanting sex.
Asexual people do not experience sexual attraction. So for example if you are a fully heterosexual woman you are not sexually attracted to other women, asexual people do not experience sexual attraction at all to anyone.
Demisexual is the same principle but that person can develop sexual attraction to specific people once they have a close bond with that person. So again using the heterosexual woman example, you are not attracted to other women but you suddenly develop feelings for certain women after becoming very close (emotionally) with them.
It's also not a choice, that's celibacy, and it's nothing to do with sex-drive/libido...which can be high or low in an asexual/demisexual person just as it can in a person of any sexuality.
Many ace/demi people also describe themselves in terms of their romantic attraction (who they fall in love with) and this can be same sex as themselves, different, both, or neither.
Because homoromantic asexual or heteroromantic demisexual is a bit long-winded many ace/demi people will use either queer or gay/lesbian/bi instead although as gay/lesbian/bisexual specifically refer to the sexuality of a person queer is often preferred as it's more accurate to the 'real' sexuality/romantic orientation of the person.
So ace/demi are expressions of who you are attracted to not what you want to do with them/how much you want to do it.