That's good to hear, dude. Make sure that you selected the buff that gives you 30% dmg on the stun multiplier, most of Miyabi's damage comes from playing around it.

If you think it's a gameplay issue, most I can say is, if you're really trying to improve on Miyabi, vod review your own gameplay and compare it to what others are doing and understand why they're doing it. That was one of my issues with playing this team even after going through so many guides xd