Pushed to the limits

I'm sick. AM is super sick. What do you do to discipline a child that laughs at you when you try? She will pinch, grab, and it hurts. When you give a time out or get mad at her, she literally laughs at you. Is my mad face not mad enough? Do I look like I'm smiling when I'm actually super pissed? What is the deal? She's not old enough to have the attitude of a teenager...whom I'm afraid has many years ahead of laughing at me.