No it’s not too late, just try hard for the hsc and prelims. To add to this, there are countless schemes that don’t necessarily solely focus on year 11 marks for example CQ university offers an unconditional early entry for almost courses based on Principal Recommendation. I did apply for this and got an unconditional entry so trust me it’s not too bad. For now try your best in prelims and year 12. Don’t beat yourself up