Greater variety in EC’s would definitely help, though being president is great.
Also, how do you rank in your school? If your school doesn’t rank, do you have an estimate of where you would stand?
I think you have a solid chance. Definitely apply to those competitive schools!
If you’d like to chance me back : http://talk.collegeconfidential.com/what-my-chances/1936230-should-i-be-applying-to-colleges-with-a-15-30-acceptance-rate.html#latest