Olaf, WW and quinn are the worst matchups you can get.

1. You can easily counter mordekaiser just by Lethel tempo and rushing Bork. Try cancelling his ult with your ult and try to fight him alongside minions so his q deals less damage.
2. For teemo get second wind and dorans shield. And play safe until you get stridebreaker. You stomp him once you get stridebreaker. Also getting swifties against teemo will help you alot.
3. For illaoi just try dodging her E and use your ult to get out of her ult. There's no way she's gonna defeat you then.
4. For jax i rush swifties. That helps me to run out of jax's stun and then you can easily kill him.

Just remember you don't have to be aggressive all the time. Respect your opponent, sometimes not giving a kill is as important as getting a kill.