Ooh! I spend lots and lots of time thinking and worrying about my future too!
I did my undergrad in chemical engineering (minor in bio) and am working on my master's in biomedical engineering. Before my master's, I didn't know what I wanted to do, but I knew it wasn't chemical engineering! I hated most of those classes, haha.
I absolutely adore biology though. I've taken classes in my masters that have to do with viruses and parasites and immunology, and I've taken an engineering course in drug delivery. So, I think what I would love to do is something with disease, possibly designing/characterizing/safety testing vaccines or therapeutics.
But.. as much as I love theoretical biology and engineering and solving problems, reading/writing papers.. when it comes to actually working in a lab, I suck! My thesis is a disaster at this point. I would have panic attacks every time I tried to go, and would throw up or pass out in the restroom in my lab building. Needless to say, not fun.
I'm not sure I can handle an actual job where I have actual responsibilities lol. But I absolutely adore learning and reading and writing fake research "proposals" for my classes (I haven't done anything real yet! bahaha)
Anyways, that was wordy wow. But since I spend like 99% of my brainpower thinking and worrying about this, I have a lot to say lol.
Are there any majors you are considering? Classes you liked better than others? and/or classes that you seemed to have more of a knack towards than others? You should pick something you love, but honestly, picking something practical is definitely good too. (But I've always erred on the side of practical - my parents basically told me I had to do some kind of engineering so I could get a job, except I could only do biomed engineering if I had first gotten a degree in a more 'traditional' engineering discipline. mehh)