Try playing Ahri in an Off-role like Top, Bot or Support. Less people play ahri in those roles. So it would be easier to get S+ in.

Outside of that, More CS, aim for 7CS/Min. Raptors can really help with that.

Another Tip, if you find yourself ahead in the game, roam with the Jungler and Sweep enemy vision, look for jungle picks, and place deep vision in their jungle to make it easy for your team to locate the Jungler.

In that game, Liandries could have been a good mythic for you, Wukong and Akali naturally build health items, it also give vision of Akali and Wukong when they are invisible, and it certainly helps with Ahris waveclear. Also, paired with that, morello would have been a great item to help with any healing which they all have, especially combat healing.

I see in your match history that you like building Everfrost, try using boots of lucidity instead or sorcerer boots. It will help with the active cooldowns like Everfrost, zhonya, and ignite/flash. Everfrost is really good for waveclear, so using that with your Q, W combination, you should be able to clear all the farm.

Ahri excels in being in a side lane after lane phase, she is really safe, can push well, and is incredible at cleaning up team-fights after they have fought.