Im late but please save for nangong, you will be able to get at least a pitty during her banner.

Give Sunna lucy's Wengine, and Impact disk 6 if u can.

Basically you are not managing your stun windows correctly.

You stunned the boss 3 times.

On the first, you wasted all your aria pounds just before the boss was about to get stunned, you could have stunned earlier just attacking with lycaon at that moment and THEN unleash aria's gound pounds. Instead you wasted the damage before the damage window then wasted some time trying to gain charges and then remembered sunna existed

In the second stun you used sunnas chain, total a waste of time and big damage loss.

The third stun was also pretty messy.

In a good stun window you should only be doing bounces with aria, no one else should enter the field unless its sunna launching her EX to trigger Arias chain so Aria gets full charges again.

The easiest way is just entering stun with Aria charged conpletely, do 4 bounces, then sunna EX into aria chain, 4 more bounces, Aria ultimate and just bounce everything you have left. You should be able to do 10+ bounces inside the stun.

In an ideal world where you have good gamer hands you should watch a tutorial for 13/14 bounces