No, it's fine to want to have an idea of what lies ahead. But, seriously, don't put too much thought into it but rather study your ass off for your hsc. A lot of people look at the start of the year and are scared they won't get the required ATAR to make it into their first preference. They even consider transferring when they have't even done their major exams yet. Transferring is harder than just getting in straight from high school. Work hard now and I'm sure you'll easily meet the requirements to make it. Good on you for considering usyd over unsw too =P