^ THIS.
I hadn’t noticed @bomerr’s push toward school led ECs. Again, this could not be farther from the correct path, especially if you are shooting for top schools. A unique EC that expresses your interests and where you accomplish something significant far outweighs any school based activity no matter how well you do at it. The key to admissions to the very top schools is strong academics & test scores, but also branching out into something unusual in ECs and doing it very well. Team captains, valedictorians, newspaper editors, etc are a dime a dozen in top college admissions. They literally see thousands of them in the HYPS pool. What turns their head is something where the student took initiative and did something new.
@bomerr - I guess me being accepted to some of the most prestigious LACs in the country was just a fluke, then. 
OP, take a look at the Common Data Set for the schools you are considering (or a sampling of the caliber you are considering). You’ll see whether ECs are considered important or not.
You have likely been misled by your peers regarding ECs. For colleges that care about ECs, they are not looking for “well-rounded” kids or kids that “give back” by taking part in community service. These are 2 of the most common admission myths HS students show up here believing. As Stanford says
The problem you face is not finding more activities in the “community service” category, it is doing something noteworthy in the ones you’ve already got. Assuming you are targeting schools that care about ECs, what you’ve got is member of this team, member of that team, joined this club. Not exactly what the most selective colleges are looking for. The question about impressive EC’s comes up regularly on the forum. There is a thread with several posts by Northstarmom, a Ivy alum interviewer, about what constitutes impressive ECs from the point of view of the most selective colleges. The post is at http://talk.collegeconfidential.com/what-my-chances/210497-those-ecs-weak-so-what-s-good.html
2 very interesting articles about ECs that stand out and how to get them (same author, different examples) are at [How to Be Impressive](The Art of Activity Innovation: How to Be Impressive Without an Impressive Amount of Work - Cal Newport) and [Save This Grind?](Case Study: How Could We Save This Ridiculously Overloaded Grind? - Cal Newport) I don’t buy into his underlying explanation of why they are impressive, but take a look at these 2 articles and I think you’ll get some original ideas.