How do you be a mother?

She has a headache. I ask her to drunk milk. She refuses. I insist. She grumpily sips some then says she just doesn't want it. So I'm left with it. 

She's eating - dinner- it's taking freaking ages. She's creating couch slides as she eats. She!: dressing with a scarf as she eats.i get madder and madder and yell at her. Spoiling g her day and mine. 

So how I do be a non nagging fun mum who plays with the kids