at one of the top universities in the nation,
at one of the top national universities in the USI find myself to be a well-rounded and creative free spirit... well-rounded means over weight. May be you meant all rounder ?
I think what samathaaaj has written is correct. Well rounded means that well balanced in a range or variety of aspects. So, it's a good key word to use for this idea.
Overall, I find this is a real good response. It's neat and tidy with all important information to convince the admission panel why you like studying at UC San Diego.
Good Luck with your application!