Do I have a chance in an Ivy league school? PLEASE HELP?

I go to a college prepatory school. I currently have a 3.11 GPA.. I did very poorly my freshman year I had a D average. This year - My sophomore year - I had an A average. My GPA factored to 3.11. Next year, my junior year of high school I plan to get A in all my classes. I am taking one AP class, and I am on 2 competitive sport teams, I am on student government, and plan on taking other leadership opportunities - like student discipline committee, and more. I also started a non profit at my school that fundraises for Haiti. I am a person that cares alot about my community and the world. I am wondering if my low GPA will prevent me from going to an Ivy League school. I really want to go to dartmouth!!!!!!!! Please let me know! I am mostly wondering if my grades from freshman year will effect big time. I also study for SAT ACT PSAT SAT2 all the time and am taking them all my junior year! Please be honest with what you think ! Thanks