(Small technicality error - You're thinking of a degree, not a "course". A course at uni is just a subject.)To be honest, I still don't know if I made the right decision myself. With the actuarial studies. But firstly I'll tell you my story.
I didn't know the actuarial profession existed until Year 10. That was when my accelerated maths teacher recommended me to be one. You could say I was interested; I didn't like Year 9/10 commerce too much but I had a weak business background, so I started researching about it. Found out that it was offered at UNSW and MQ. But being honest, all I knew was that it involved risk; I didn't know anything specific about it.
Year 11 came, and I transferred schools (old school only went from 7 to 10). Pure mathematics became something I was interested in. It was my physics teacher who suggested that I consider it, because he knew what kind of math brain I was. Although I was somewhat sceptic in Year 11. I had the mindset of - I will certainly take maths up as a double degree, just for the hell of it. But where would maths get me in life? Ironically, at the time I thought a science degree would get me further in life than a maths one.
By that time, a lot of people knew that I was thinking the actuarial direction. Because I was recommended for something since Year 10, I always kept it at heart, thinking that's what I will try out. Because trust me, I was also completely clueless. I didn't know where the hell I wanted to be in life either. Although, unlike you, I didn't even know what faculty I wanted.
Come Year 12, I soon realised from a motors assignment that I did not want to even touch engineering. Screw it; designing stuff is too painful.
Which left me with only business and science anyway. Because I knew I wanted to do some level of maths. My physics teacher kept pushing for the pure maths and I was becoming increasingly convinced. Come open day, I got sold. I knew i wanted to study maths no matter what.
But I felt if I just studied maths that would be boring. That's why I kept to the idea of a double degree. I thought for a long while that I wanted actuarial, then in December I started to back out because I thought maybe I wanted to do computer science. Simply because I didn't know if I wanted to go into business anymore. Plus computers felt interesting, and honestly our world revolves around them.
I just stuck with actuarial because I thought a) I managed to make the cutoff (somehow) and b) it's been my target since Year 10. May as well try.
I got into actuarial, and struggled. No idea at all how I survived this semester. But I'm convinced enough to push, because if I can do it now, hey, maybe I'll be able to do it in the future. Provided I can maintain my new-found like for business, I should be able to survive. (I still struggle a bit with getting used to the business-y world.)
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Now, back to your situation. As mentioned, you definitely want to think about where it is you want to work. Like, if you are very interested in veterinary roles then good for you; keep thinking in that direction. But to what extent are you convinced that you want to give it a shot?
And if you're interested, are you willing to put in the effort to get in? Sure, it may be really hard to get in, but are you one of those people who will think it's too hard and dismiss it, or be the one to push as hard as possible to ENSURE you get in?
Because, honestly, if you're leaning towards the latter than you raise your chances a bit. Because you will force yourself to get that far. It's just like me; I had actuarial on my mind and whilst I prepared all sort of backups, I ended up not needing it. Because for some reason, and to this day I have no idea how, I got in.
Also, transfers are very common in uni. A lot of people go back on what they thought in Year 12. That is also OK, so do not dismiss the idea.