“Here’s my question: Given the fact that I start most of my activities in 11th grade, am I disqualified from any Ivy League Schools or Top 20 Schools?”
I don’t know if you realize it or not but a lot of those top 20 schools are small and they have limited seats. Unless you have a hook, that they want, you will probably be rejected from them, regardless of how many EC’s you do. They just don’t have the room for all of the hundreds of thousands of great students who apply there.
So although you can apply, assume that it’s a matter of luck, and it doesn’t matter what ECs you now do.
That doesn’t stop you from applying. So apply, but also apply to all of these other great schools that will fit you.
I would suggest that you start looking at jobs now for the summer. Start doing some research. I know that, in our area, all of the jobs for high schoolers, such as the amusement parks, zoos, museums, etc. start looking in Spring for their summer staffs.
Someone has directed you, incorrectly, about what your focus should be. You are supposed to do activities that help you to understand who you are. It doesn’t just have to be specific to the major that you hope to study.
It’s a good thing that you did participate in Swim. The Swim team is a really respectable EC. Even though you didn’t stay with it, it’s still something that you want to report on your college applications.
The reason I say this is because the colleges and universities like to see people who go out of their comfort zones. Swim shows discipline because you’re not only doing your studies, you’re also performing some very physically hard practices at insane hours of the morning and evening. It is definitely not an easy thing to do that’s why the colleges like it. It demonstrates discipline and good time management. So don’t neglect to put that on your application. Please remember that all of the admissions counselors, at the colleges and universities, went to high school and a number of them did swim team. They know what it’s like to be on the swim team.
When our children did swim they had to get to the school at 5:30 (breakfast was provided after swim practice), then I didn’t see them till after dark. Did they hate the practices? Yes, that’s why they didn’t last in it, but they continued to other sports that they loved!
Just remember, if you’re doing computer software studies you can go to any university and you will be very employable, at very many different TECH companies. One of my kids went to a top 10 and is the CS engineer at a big corporate company. Our eldest went to the State University of New York, a public university. She majored in electrical engineering and computer software studies- it’s called EECS. She graduated and continues to go straight up, not only in titles and wages but in accomplishments.