I just don't understand Lee Sin as a champion.

I love early game junglers. I love junglers that can get in the face of the enemy jungler and cause pressure just by existing. My main champ is Jarvan, who excels at all of these things.

I also play elise, gragas, but not to the same level.

One champion I've ALWAYS wanted to play is Lee Sin. I actually have either M6 on him or M7 on him, but I don't think that's really because of skill, rather than quantity of games. I don't FEEL like I know what I'm doing on the champ.

I can execute some pretty gnarly ganks early game. I'm good at hitting his Q. I use his entire kit, not just his QQ combo. I shield my allies, I know how to use his spell vamp on his W to good effect. Like... I know what his kit does, and I know how to use it (kinda?)

What I don't understand is what the hell I'm supposed to do on this champ after 15 minutes.

Does anyone have any advice? I'm not mechanically gifted enough to pull off the ward hop flash kick insec thing reliably. But I've seen plenty of players find success on this champ even without those kind of high level mechanics.

What's his role in mid-late fights? What am I supposed to be doing?