I’m not exactly sure about what I want to write as my intended major and career plans, and I feel like putting undecided might give me a disadvantage.
I’m sort of considering double majoring, could I convey that in my application?
And would it be odd if I pick an intended major but not an intended career?
Also, if I pick an intended major will I be expected to show that I’ve been involved in something that shows my interest in that? What if I just realized that I have an interest in something a few months or weeks before submitting my applications?
Applying as undecided does not put you at a disadvantage at the vast majority of schools. If you don’t know what you want to major in, go ahead and apply undecided.
If you don’t know what you want to major in, how could you know that you want to double major? If you apply undecided then don’t worry about conveying that you want to double major.
No, it’s not odd to have a major intended but not a career. You’re also not expected to demonstrate a string of uninterrupted interest in an area from a young age. Colleges don’t expect you to have everything all planned out from age 13. Lots of people change their major even after they get to college and then change their career focus after they leave. (For example, I applied to my college as a pre-law political science major; changed to psychology at college; studied public health and psychology as a graduate student; and now I work in tech.) Life doesn’t actually happen in a straight line.