Ok. so first of all, you probably want to pick up one, maybe 2 more events.
The following image describes which events run in which time blocks (regardless of team number) at nats.
since when could my images be only up to 500 pix wide?
Noting that the nats schedule is often used by invitationals, you will most likely be unable to do both Astro and Circuit Lab.
I'd recommend picking events on
a - your strengths
b - your resources
c - competition
Strengths need not be explained, but resources include not just materials and tools for builds, but also textbooks and advice for study/labs. (e.g. - do you already have a couple textbooks covering the topics in a certain event, or are your parents able to help you). Competition is noteworthy not just within the context of no one will fight for you over the event, but also that it will be picking up slack for the team if you become good at it.
On becoming good at events, learning style is up to each individual, but a good measure is to see if you can teach someone how to do it. Don't settle for being able to place but not be sure on most of the questions; in order to succeed you should be able to take a SciOly test and come out of it feeling as if you had just taken a standard test in a subject you're at least half decent in - AKA you knew most of the answers solidly and had a good educated guess on the others. (though there will always be those 1 or 2 questions)
That's what I got for individual performance. Keep in mind that partner as well as team interactions are also important.