Stressed out high school student...

<p>So, my dream is to attend Columbia University in New York and major in pre-med.
I have just started my junior year in high school. So far, my unweighted GPA is a 4.3 (or a 5.05 on my school's scale). I am #12 in the class out of 425, I am an all state player in band, I am an officer in NHS, I volunteered at a hospital over the summer practically everyday and received over 300 hours, and I will be going to Iran this summer to volunteer at hospitals there.
I am not a straight A student, however, and I have made a few high b's on my report card (only in math classes), but all of my a's are at a 94 or above. I know that schools like Columbia are highly selective, and highly competitive, but I just want to know what my chances are, and if you guys have any suggestions on what to do to make me stand out even more among colleges such as Columbia.
I am especially stressing right now because in the first grading period, I had 95's and above on my report card, except for Pre-AP Pre-Calculus, in which I had an 81... I am taking 3 AP classes this year, and the rest are pre-ap. I have taken 5 AP's total.
I'll be thankful for any piece of advice I can get!</p>

<p>Very strong application… however, Columbia and schools like it are SO selective that you might be a little hobbled by your B’s. Get Honors Pre-Calc up to at least a high B, and you’ll have a better-than-good chance. :)</p>

<p>Thank you so much! And I’ll get it up to a high B. Don’t worry. hahah.</p>