I found this fanfic in AO3 site. This is like one of the best harrypotter au fanfic i've read so far. 

https://www.asianfanfics.com/story/view/922189/heart-of-magic-eunhae-harrypotterau

and her other eunhae fanfic also so good. glad i found the site and that author 😊 just sharing lol