Hey Sarah!
I’m assuming you mean 2x Year 11 subjects (Unit 1 and 2) here. I personally did 3: Psych, General Maths and Chinese SL, although I’ll admit that 2 would’ve been better (and I only did Psych U3/4 in Year 11).
In terms of prerequisites, it really depends on what you’re intending to do or are considering to study after Year 12 i.e. what sort of courses are you looking at for uni? The VCE sciences tend to be mostly one of multiple options for prerequisites e.g. doing at least one of Psych, Bio, Chem or Physics will often be a prerequisite for a Bachelor of Science at Monash, if that makes sense. What areas are you hoping to head towards after VCE?
As RedPanda has mentioned, fairly manageable if you invest the effort and once you get the swing of things. Please don’t neglect your Year 10 subjects too often though! They will be crucial in building fundamental skills for future years, especially in English and Maths.
In terms of choice, if science is your thing and that’s where you want to head, then by means, go for it. (I may be a little biased...
) But also keep in mind any change you may also go through. If your interests and skills are diverse, then remember to have a little wiggle room in case of a career change.
My number 1 piece of advice for your situation is definitely pick subjects that you enjoy a lot! If you enjoy the subjects you do, this will make your study a lot less of a drag than if you’d purely played to your strengths or to scaling (these are common mistakes). Some people may also offer the advice of doing “heavier subjects” first, so that might be something to consider as well.
Hope that helps!