You are 21. At 21 I thought I'd made all kinds of mistakes too. In fact, I had! But you've only had about 3 or 4 years of quasi-adulthood to make them!
At 21 you think you've had a past, and you have, but your past is almost entirely a childhood. Mistakes you have made in your past at 21 are mostly childhood mistakes.
By the time you're 34 (as I am) you'll have had 17 years of adult-esque time to make all kinds of mistakes. You'll have also had all kinds of time to make major changes and accomplish major things.
Unless you had a truly horrific past, at 21 you can pivot to doing almost anything.
This is especially true in university. In undergraduate at university I switched majors from International Business (about 8 months until I fell in love with 100-level Economics) to Economics (about a month, until I realized it was all math) to Philosophy (about a year; it was really fun but I didn't want to do it professionally) to Cognitive Psychology (which I completed a major in) to Computer Science (which was the other half of my double-major). If you add that up and include co-op work terms, it took 6 years! At the end of it, did I wish I'd had the "wasted" time back once I was a software developer? Sure! I'd missed a good portion of the dot-com boom, and it would have been really fun, presumably :) But I learned a lot from the "wasted" time, and that's what undergraduate is for.
Everyone in their 30s (and older) will probably tell you that you have "so much time", and I'm sure it's infuriating to hear about all the choice etc when you probably don't have much money or direction. But you also presumably don't have a mortgage or children! So, you have more "degrees of freedom", in that your income requirement is a lot lower. So, you can make huge changes with a lot less risk than when you're older. You won't realize how huge an opportunity that is until you are older. But trust me: it is.
TL;DR - Don't obsess over your supposedly wasted time; you've hardly had any time to waste. Take some time to decide what you want to do and become, then figure out the next action you could take to get slightly closer to that goal. Then repeat as necessary.
At 21 you think you've had a past, and you have, but your past is almost entirely a childhood. Mistakes you have made in your past at 21 are mostly childhood mistakes.
By the time you're 34 (as I am) you'll have had 17 years of adult-esque time to make all kinds of mistakes. You'll have also had all kinds of time to make major changes and accomplish major things.
Unless you had a truly horrific past, at 21 you can pivot to doing almost anything.
This is especially true in university. In undergraduate at university I switched majors from International Business (about 8 months until I fell in love with 100-level Economics) to Economics (about a month, until I realized it was all math) to Philosophy (about a year; it was really fun but I didn't want to do it professionally) to Cognitive Psychology (which I completed a major in) to Computer Science (which was the other half of my double-major). If you add that up and include co-op work terms, it took 6 years! At the end of it, did I wish I'd had the "wasted" time back once I was a software developer? Sure! I'd missed a good portion of the dot-com boom, and it would have been really fun, presumably :) But I learned a lot from the "wasted" time, and that's what undergraduate is for.
Everyone in their 30s (and older) will probably tell you that you have "so much time", and I'm sure it's infuriating to hear about all the choice etc when you probably don't have much money or direction. But you also presumably don't have a mortgage or children! So, you have more "degrees of freedom", in that your income requirement is a lot lower. So, you can make huge changes with a lot less risk than when you're older. You won't realize how huge an opportunity that is until you are older. But trust me: it is.
TL;DR - Don't obsess over your supposedly wasted time; you've hardly had any time to waste. Take some time to decide what you want to do and become, then figure out the next action you could take to get slightly closer to that goal. Then repeat as necessary.