Inconsistent games? What is going on here?

There are games where I carried, there are games where I fed. There are games where I had 180 CS in 20 minutes and games where I had less than 120! There are games where I remember to ward, there are games where I forget. There are games where I win, there are games where I lose. And you know how this cycle goes.

So how do I stay "consistent," and why is this happening?