The fact that you were not charged is a good thing. However, an agency would likely consider how many times you have stolen from cars (or stolen at all), what you stole, and how long it has been since you've stolen anything. Obviously, the fewer number of times you've stolen anything, the better, and the longer it has been, the better.
Don't drink alcohol again until you are 21. Don't smoke any more marijuana, and don't do anything else that is illegal!
I would suggest continuing college after you earn your two year degree. Earn a four year degree! It will make your application better, and put more time between your indiscretions and when you apply for the police academy or with police departments.
I would focus on your education, and then apply to some larger police departments that would send you to the police academy.