Hi Gmfarah1!
This reply is a bit late for your SAC, but applies well to the final VCE:
1) Based on what you have done so far, you are progressing well, and you are doing all the right things.
2) Now, it is good you start familiarising with CAS! If you want to get a really high score, you must tackle difficult problems and they often need a mastery of CAS. To paraphrase Colonel Kurtz from Apocalypse Now, CAS is your friend. If it is not, then it is enemy to be feared. If you are master of it, you will do well, particularly probability and calculus. But it is easy to make little mistakes if someone is not fully familiar.
3) Past exams are very useful, but I am amazed with the creativity of the people producing the VCAA tests - every year they have new original problems! Exam in 2018 is not a good predictor of what will come this year.
4) Quite a lot of the analysis of Maths Methods exams since 2006 is in
http://www.tmvscientific.com. There is a plenty of demos to check before you decide whether to order it or not.
Cheers
Nirvana