Ain't I a sister as well

They say I shoudn't believe in sisterhood, not even the concept. That it is an contradiction i terms, that it is false per se - there are no sisters in the world, no sisters in history, none in future. Might be, I may be naive. But does the world become a better place just if I stop believing, hoping, longing (for you, something else, other than this)? And if there only is few of us, doesn't that count?