You're only doomed in an existential sense. In terms of grades, you're actually doing pretty well.
With special consideration for missing a term: I think you should be able to get it, personally, but I don't know anything about the official stance. In any case, you probably wouldn't be able to get it from the VCAA, but the universities you apply to may be able to help you. Ask around, email people in admissions particularly.
Lastly, it's difficult to tell how you're actually doing because you haven't sat any exams. If you do well in those, the grades you've been getting for SACs will become less important. So, to do well, you definitely need to study well for exams. It's too early to be doomed yet!