OP, I kid you not, but I am/was just like you. I thought in my final year of high school I would've figured it out. That is, settled on a career path and spend the next 4/5 years of university pursuing it. But that never happened. I pretty much enrolled in university because that's the next best step out of high school, right? Go to uni, get a degree, and all your dreams will come true? False!
I spent the first 2.5 years (.5 for the summer) of uni "figuring it out". In retrospect, I wish I had taken a year off earlier (or even right after high school) to figure it out, because those 2.5 years, albeit fun, were expensive, and a waste of money and time. I did end up taking a year off, got myself a commission base retail job (the commission structure allowed me to maintain relationships to make sales) and pretty much used that time to consider all the career options I can be successful in, and simultaneously enjoy.
I'm not advocating to go work retail, but it allowed me to meet and interact with so many people from various fields, one of which I am pursuing and graduating in this spring (CS). Like you, I thought CS entailed sitting behind a computer screen in an office until I hit 60 (for some that may be the case), but your career is what you make of it. The guy I met in CS while in retail, worked remotely and he had the option to work in different countries (Canada was his 3rd remote location). So that pretty much changed my assumption of the field.
So backtracking a bit, and comparing my grades/performance pre 'year-off' vs post 'year-off', you can see a considerable improvement. I think having a keen interests in a particularly field translates to your work ethic and performance in school, and post school. So you may not have no real interests in anything, and I'm not here to tell you go do XYZ major, but I can tell that you're kinda smart, being able to transfer into Sauder from 1st year Arts, heck, even being able to get into Uni in the first place (unless you're international or your family name is on one of the school buildings...</joke>). That being said, take this summer to reach out to various folks from different backgrounds, connect with them, and don't go assuming anything.