I'm now interested in Medicine, Dentistry, Law and Commerce (Investment banking in particular)
I'm not particularly concerned about the pay, I just want to do something that I will enjoy and can see myself doing for an extended period of time.
There is a serious contrast in what you claim to want and what your choices suggest you want.
I would suggest seriously re-evaluating how you decide what interests you. As sluu so succinctly said, you only like the romanticized notions of these careers - you need to spend some time researching what each career entails (not how prestigious you think it is) and what type of subjects you study in each career, to make an informed decision on your future.
I have done lots of research about each career and even spoken to people from each career about what their job entails, what their lifestyle is like etc. Have also looked at all of the subjects I old study at university for each profession.
I'm not just blindly deciding, "hey, investment banking sounds pretty cool and prestigious".
Ok, in that case, do you mind justifying it for me? i.e. What do you like about each career, what subjects do you particularly like in each case and why you want to be each profession respectively?
I wouldn't mind justifying myself at all if we were conversing face to face or orally as it would be much easier to communicate a large amount of information to you. I just can't be bothered typing out heaps of stuff at this point in time because I'm very tired and have a SAC tomorrow that I'm not ready for.
My justification for medicine and dentistry specifically is that they're both careers in which I damage a positive impact on the community at large and are heavily embedded in the health sciences field for which I am passionate and really enjoy learning/reading about.
Okay I'll put in my little spiel from personal experience, about people who want to do medicine and whatnot - this may apply to you but it also may not

.
So many people in my school who are amazing at maths, relatively introverted and the "quiet achiever" type want to do Medicine. More often than not they study really hard in Biology (for example) and are relatively uninterested, then get incredibly good scores in mathematics subjects... yet it's not a maths related degree they do, but MEDICINE!
Whenever I ask them why they want to do Medicine (and a lot of people want to do medicine at MHS), they pull out the generic responses; I love helping people, I love science, I want a good solid career... sometimes people just say "I don't know what else I'd do" or "I don't really care, just do med." People think they're making their own choice, but when your close family has been talking about "how respected doctors are, how much money they make, how good a career it is" for the past 14 years of your life, even if your parents don't directly say "You have to do Medicine!" (which happens to lots of people), you're still being brainwashed into thinking "Med is the best" from the get go. Also, I don't really buy the whole "I love helping people" as for most people, that isn't the real reason why they're choosing to study the degree - it's a lie they tell themselves to justify their decision.
Again, that's not to say this is everyone... I am just constantly frustrated by the amount of people who would be great engineers, scientists or businessman, who limit themselves to Medicine because of some ridiculous societal/family expectation and ill conceived notions of prestige and wealth.
I really hope people don't get offended by this post, and I'm not aiming it at ANYONE in particular - a lot of people (I daresay more then half) will go into med for the right reasons and become great doctors, it's just imo a substantial minority who are doing it for the completely wrong ones.