So many things to do, so little time.

[Siri]

You do have time. If you put yourself on the right track today and stick to it--nil volentibus arduum. [There are probably better phrases, but I know this one's right.] 90 years is exactly as long as you make it.

Just a note: understand that this means accepting your 'failures' as well as your successes. Don't get into CalTech for undergrad? Don't worry about it. Find a school that works for you and excel there. CalTech will look at your for grad, if that's still what you want. You'll screw up sometimes (I do it quite regularly), don't let that get in the way of your motivation.

The PSATs serve two purposes. National Merit, and telling you to study more for the SATs. Listen to the latter and you should be fine.

P.S. I'd check your Latin. I don't know much about Latin cases, but grammatically you're looking for the plural of the neuter (I assume) accusative. I would think it's omnia.