Aahhh, yes, I remember who I was at 17 y.o., too. My diaries sound a little like yours, siy.
Word in yer shell-like, experience counts or a lot and, you have two ears and one mouth. Pays to listen twice as much as you talk. Until you've gained a broader perspective/greater understanding of ppl/objective awareness of your own weak points.
Dear ol' Dad used to say,
"At 16 it's amazing how thick parents and grown-ups are. When you're 21 it's amazing how much they've learned!"
I say that to say this. Take failures as they come. You're not going to make it in everything and along the way you'll start to figure out what's worth it and what's not.
FWIW