Should external rotation naturally occur or is it safe to try and throw your arm back while throwing to achieve more?
Throwing your arm back probably wont do much for you. Make your mechanics sound and throw a lot and the external rotation will take care of itself
It’s possible your arm slot may have something to do with it. How do you throw—straight overhand, 3/4, sidearm,or anywhere in between? Take a look at how you throw—if your arm slot is in one of those in-between categories, not to worry; just let it happen naturally. Over the top may be another story—maybe you can get a good pitching coach to watch you throw and maybe he will have some ideas. 8)