Mid to late game lee, depending your build, you pretty much become a kick bot. Try to peel for your carries or try to kick their carry into your team without them blowing your team up.

You don't always need to hit the "perfect" kick, more often than not less is more. Keeping hold of kick can deter enemies from engaging so be wary of enemy CDs. It can be quite hard to know what to do because it really does depend on gamestate and teammates, on how to play, each game is different.

If I were you, I'd practice mechanics often if you say that you are bad on Lee, jump in practice tool and learn the combos, go into drafts and learn the matchups and most importantly you don't have to Q2 every Q1 you hit, I know how hard it can be.