Try using as much wrist as possible. Right now you're using only fingers and surprisingly arm. At slow tempos use wrist to stroke out every note, at medium tempos start to lower stick heights and use more fingers. Finally, at fast tempos stick heights should be around tap height and you should mostly be using finger. Hope this helps.
In my experience, this is the opposite. It's true that you should stroke out diddles at a slow tempo, but use mostly fingers at a slow tempo and it's all arms when you start to increase the speed because most peoples fingers cant go that fast.
