is so self-absorbed... like so ditsy and inconsiderate, and often she gets offended.

Your sister is not mature and neither are you in your enabling of her dirty habits.

There is nothing immature about calling someone out on their gross behaviors, especially given that you’ve already attempted to do so in a civil manner.

Looking to still have a good relationship with her, not create a family drama.

Given the point of your entire post, you already lack a good relationship with her! Her behaviors have already created drama in your life, as you’ve implied in your original post.

Unless you want to get a higher authority involved or you want to have to keep bugging her, take action.