My 9th grade year just finished up and i ended with a 3.3-3.4 unweighted. My classes this year are harder than the classes I will have next year. I am retaking a few classes ( need on opinion on this), but next year i hope to bump my GPA to high 3.7 or low 3.8. I took a practice SAT and did very well. Also I am on varsity tennis, robotics club, student action senate, JV golf, volunteer at red cross, also captain of chess club. My school is top 10 in the state. I know I can get straight A’s next year, this year I was dealing with anxiety and was immature. Do I still have a chance? Thanks!
My Freshman year I got a 3.0 gpa and had almost no extracurriculars until Junior year. I ended up in the end of my senior year with a 3.8 weighted and I still made it. Relax, this isn’t the end of the world, it certainly would help however to get straight As the rest of the time to bump up that GPA high. As for retaking classes unless you completely bombed one(a D or F) I personally dont think it necessary, however, the decision rest with you whether or not you deem it necessary.
I was once a high school freshman and I remember how paranoid I was about college, so I understand your concerns. However, with all due respect, you’re being rather silly 
Yes, a 3.3 is low for Vandy, but that’s just ONE year. Your chances at Vandy are definitely not over. Upward trends are good, and you can easily end your high school career with a ~3.7-3.8. Nothing to worry about. If you get a 3.3 in your sophomore year as well, it might be appropriate to start panicking. Just get straight A’s from now on and you’ll have a great shot. Your ECs look great btw, keep it up and rack up those leadership positions.
Also, I would not recommend retaking high school classes. Unless you failed one like Axelarate said, it is completely unnecessary. However, if you did get a D or F, I think it might be necessary to retake it, as some colleges will not accept that class as a prerequisite (like math for example).