Hello, hagureshinma! 👋
Great work! Your BEM looks very good. About Sass file management - i would suggest you to keep media queries in files where you use them. It would be very uncomfortable to keep jumping into another file to see how the element behaves after applying media queries styles. Look into my projects to see how i manage to do this. I use MIXINS for breakpoints. Also read about Sass 7-1 pattern to keep your files orginazed.
Good luck with that, have fun coding! 💪