You should really cleanup the layout of your code. Use indents carefully.
If you do so, you will see this:
potVal = analogRead(PotPin);
{
That's not okay, allthough the compiler doesn't mind.
You set the motor every millisecond ! That's odd.
Your button might bounce... wait, I refrase that: Your button is bouncing.
You may use A0-A5 for digital pins, and also 14-19. It's all valid.