Hey worldno1!
Congrats on finishing your first set of HSC assessments. Make sure you get the rest you deserve before getting back on the study grind!
Maintaining ranks was a big deal for me as well so I understand how you feel. The 'what ifs' always got to me in between my assessments, which affected my preparation for my upcoming tests. What I figured out throughout my HSC was that I needed to look at the bigger picture. It's more important to do well across all of your exams and be consistent throughout the year, rather than mentally exhaust yourself by over-worrying after each assessment block and possibly, affecting your preparation for your next one. If you receive any disappointing results for this set of exams, don't be too upset as they tend to have relatively low weightings and - trust me - there are SO MANY chances afterwards for you to redeem yourself and achieve your previous estimate or goals. Rather think of this set of tests as an opportunity to figure out the areas you need to work on or improve, for you to score higher and not repeat the same mistakes in the more important exams (mid course exams, trials, HSC).
Also, don't forget that year 12 is a LOT harder than year 11. There's a lot more content to cover, skills required to excel, and it is also a very physically and emotionally draining experience. So don't feel the need to constantly compare your year 12 performance to last year's. Once again, focus on mark and performance maximisation across the entire year that is ahead of you. Good luck!