Why does my family want me to be a girly girl?

There are a lot of potential reasons. They might have always thought of you as a girly girl and be afraid to consider that you aren't. They may also feel that you need to be "girly" to fulfill a stereotype that rounds out your family or to placate other family members or friends. Maybe they don't even realize that they're pressuring you to be someone you're not. If possible, try to talk to them about why they want or expect you to be a certain way, and how they can support you in who you actually are rather than in who they want you to be.