I guess at the end of the day, you will only be marked on how well you answered the question, so although your essays may be of 18+/20 quality throughout the year, however, if you didn't answer the given essay/creative/short answer questions to a sufficient extent on the day of the examination, you will only be marked on how well you answered to a specific question. I guess one of the difficulties of HSC English course is that you will not get marks for showing the breath of your knowledge about a text, but rather for showing the depth of your knowledge on the specific aspects relevant to the given question.
Well-good luck on the optimistic hope
I guess you don't really need an external confirmation, you should know yourself whether you have put in everything you could have into preparing for the English exam and studying for English coupled with the demands of all of your other HSC subjects. You are likely to have tried your best-and that's all one can ever ask
The only thing I am hoping for right now is to get an offer into the course I want to get into and hopefully do well in it