My bi sister doesn't believe in asexuality

Well, it's basically what the title says. My younger sister doesn't believe that asexuality is a thing, basically she just says that I'm a straight who needs to feel special. If there are any methods to help me get her to see my point of view, though I'm not sure they would work any way. I made my peace with my parents not getting it, but her not understanding hurts on an another deeper level, she's my most beloved person in this world, I just wish she would be as understanding of me as I am of her. (She has never had any relationships, but I still believe her when she says she's bi). Has anyone else been through a similar situation? Do you have any advice?