Nonstop Attacking

Hello! Let me tell you a story to start off:

My mouse is an Apple mouse. My laptop is an Apple laptop. Maybe you can already sense my family likes Apple. Anyways, we can't afford much more than that. People tell me to go buy a gaming mouse, but I don't really want to spend money just for a mouse I'll probably use for a month, and then stop using it because I am getting bored of LoL.

With that, I have a problem in the game. I can't stop attacking once an enemy is nearby. So it is extremely easy to lead me to a turret, and kill me. This had happened countless times before, but there is nothing I can do. I tried pressing S, or H, but I continue attacking, and I still can't walk away. I know you have to press the right button on a mouse, but the Apple mouse has one one big clicking button thing.

Is there a way to stop attacking? Because I am getting tired of people saying,"You shouldn't camp out under the turret," or "stop attacking, and leave," and even better "you are being stupid, stop attacking, jesus!" or my favorite," I have an idiot as a teammate."

So, any suggestions?