Which career to chose if i have little time to study?

Okay, this is going to be long, but I really need honest advice. I'm sixteen, i made 16 years in this april, and i'm trying to find a career purpose for some months now,. since everyone around me already knows what they want, im running out of time.

So basically, I’ve been here before. I went through a whole phase with astronomy where I forced myself to like it because I wanted a purpose. It wasn’t natural. It felt like I was dragging myself with weights attached. I’d sit there studying things like dark matter and instead of curiosity, I felt dread, because there were no clear answers, no visualization, nothing I could touch or apply. It felt too abstract and out of my control. Like… I can’t change Jupiter’s orbit. There’s no “mechanism” to interact with. I thought I'd never be able to touch a black hole or even see one, and that gave me an existential crisis.

Eventually I realized I didn’t actually like it. I was just trying to fill a void.

Now I’m terrified of repeating that mistake.

Current situation:

I’m in my second year of high school and I feel like I’m running out of time. I need to start studying seriously, especially if I go into something like engineering (ITA/USP level, which in my country Brazil is like, insane hard, most guys who enter ITA started studying in 8th or 7th grade so im already lowkey fucked). But I feel completely stuck.

I’m mainly between:

Engineering (aeronautical, nuclear or mechanical, but i dont want to worry about this yet)

Politics / geopolitics / economics

What I’ve noticed about myself studying and researching:

I genuinely enjoy and LOVEEEEEEE physics. Even when it’s tiring, I want to continue, it gives me energy, i love understanding how things work, the “why” and “how” behind systems, i liked learning about jet engines, combustion, aerodynamics, turbulence, etc, I also like war/geopolitics — especially understanding why countries act the way they do (ex: Iran vs US, Ukraine war).

BUT:

I don’t like ambiguity that much, i don’t like things that feel purely interpretative with no clear answer, i don’t like overly abstract things I can’t visualize

I like engineering. i like t. I really do. But I have doubts:

I’m not super “creative” or revolutionary, i dont want to create anything new. And the biggest thing in my mind rn is:

What if I spend 2 years studying engineering and then realize it wasn’t for me? All this time being wasted when in the end I was born to be... I don't know, a political analyst? I don't know what to do, and it causes me so much anguish because the answer is inside me, right? Everyone knows what they like, why can't I figure out something that's literally in my brain right now?

Politics: Some topics are interesting (especially current conflicts)

But a lot of it feels… boring or too interpretative, i don’t feel like I have a strong “cause” or something I’d fight for, bcs i know most causes will never ever be solved (war, famines, crisis and etc) I don’t even like Brazilian politics that much

If I’m being honest, what attracts me is more like: strategy, wars, and understanding power + big global decisions (since im eleven i have a plenty of ww2 books!) but i dont wanna be a diplomat due to some incompatibilities with my future plans

What if I commit again, like I did with astronomy, and waste years on something that was never truly “me”? I’m someone who works best focusing on ONE thing. I get overwhelmed easily with multiple goals. So “just study both” doesn’t really work for me.

Today I:

watched videos about aerodynamics (loved it)

watched geopolitics content (also interesting, but in a different way)

And now I’m even more confused.

I’m really anxious about this.

Like:

Why can’t I just KNOW what I like?

It feels unfair that I need to overanalyze this much just to understand my own interests.

What if I study engineering for 2 years… and it was actually politics? What if I fill 400 pages of physics… when I should’ve been studying wars? What if the opposite happens?

Both scenarios scare me

I recently bought a 400-page notebook to start studying seriously!!!!!!!! I want to start (like, really badly), but this indecision is paralyzing me!!!! Imagine what I could have learned about mechanical physics in these months that I've been reflecting :(

If you read all of this, thank you. I genuinely need outside perspectives because I feel stuck in my own head. im even asking my teachers and classmates for advice