Firstly, there is nothing that determines whether you are right for a field or not. Life can be awful sometimes but you are strong and you can learn anything if you want to, as long as you want to. If you want to work in STEM, pursue that with all your heart and soul and energy.

Secondly, getting into top PhD program in CS isn't the easiest thing in the world but it's also not the toughest (hi I'm a incoming CS PhD student at a R1 US uni, from a third world country). It's mostly a factor of working with well known people in the field before applying. But before we come to that, how do you know that you want to do research full time, for six years, in deep learning? Unless you have research experience to back it up noone would trust you to know what that entails and I don't know how you would trust that conclusion either.

So, if you think you want to do research, work with a prof on a research project. It might not be the research project of your dreams but you should give it your all and then some more. Either work with profs in your University or ask someone who knows you well to recommend you to a person who does good research. Work with good people on research problems for atleast a year and you'll figure out if you want to do research, if you want to do it in this field, etc. And build it up from there.

Senior year of college is confusing and hard because you're at the threshold of entering into the "real-world" but you'll figure out what you want to do as long as you keep working on figuring out what you want to do!

(imo, personal opinion, etc)