Struggle late-game, especially as a top laner.

Hello. So I have been maining Akali for a little while. She's actually my first champion to 100k mastery points :D

Anyways, I prefer to play her mid. I feel like it's easier for me to snowball from mid than from top. However, once lategame comes I struggle a lot. I can't seem to close out games, and it's very frustrating. Especially when I am fed.

When I play toplane it's especially hard as my team often times have no good front-liner. If we don't manage to end out quickly they just end up winning the game because the beefy tank.

What should I focus on lategame? Split-pushing, teamfighting? How do I actually close out games when fed?

Also, am I supposed to have an easier lane top than mid? I do much better mid than top. When I play top I feel like I lose all kill-pressure when they get their first tank item, yet they can skill kill me no problem.

Thanks in advance.