I've dislocated my shoulder around 13 times, and I went to see a chiropractor to help out...I don't want to talk down surgery, but there is a lot more to your shoulder than just the ligaments. You're body is a system of subsystems that interplay with each other. You may fix the ligaments with surgery, but there is still a lot of other work you gotta do to strengthen your shoulder
Basically, my chiropractor told me that you're ligaments should never take that much stress. You're muscle is a huge player in stability, those "stupid" physio exercises suck and seem pointless but they are really awesome. What happens when you dislocate your shoulder is your shoulder pops before the muscles can contract, and so you have to train you muscles to be quicker by those exercises and high reps of them
Also try standing/sitting up straighter in general, you're back muscles can get real weak by the sitting in classes/standing hunched and what not and that all relates back to your shoulder.
While skiing, tape it up and brace it up, it can't hurt and provides extra padding and eliminates out of range motions. Also, try to teach yourself safe falling techniques to absorb shock and allow stronger, more muscular parts of your body to take the hit