I'm glad to hear that, honestly I'm like you. I have a friend who's 16 and that's it, the rest of my friends are, matter of fact, way older than me, I honestly like hanging out with adults, speaking with them can be very interesting.
I'm glad to see you are working hard, I bet it will eventually pay off and don't sweat it, STEM has a pretty good future I believe. I finally finished my first semester, just got 10 semesters left haha😂. I'm really happy actually, now I have legal books in my room and I love them, they will probably stack up and become a problem but for now they look good, I'm glad I got into a double degree for both Business and Law. I love business, but Law is much better, it's a year more of studying but now I'll know both of them.
I don't know about the US, but here collegue isn't really that big of a jump, I'd say by the time you are 16 it's as hard as it gets, after that you just have to endure on the same level.
I'm personally learning Japanese, and I'm kinda happy with my progress and these months I've really gotten into Pokémon, I specially love the TCG, I've got a bunch of rare cards (not that special, just spent about 25$ on all 4 of them) and a few decks, I also love travelling and exploring both nature and the farthest and strangest places of my city, how about you? Best wishes