Improving in math is more than possible regardless of its level. There are multiple things that can help your improvement. Regarding tutoring, it eliminates confusions and potentially provides you with resources that target your weaknesses BUT it does not guarantee you great marks. It makes it easier to learn but doesn't necessarily make you learn. "Practice, practice, practice" is a common advice you may have heard tons. Practice is attention, rehearsal and repetition and it helps a lot in learning something effectively. What often works best in math of any level is
consistent practice. This means practice (do questions) frequently and often most days or everyday each week. This might sound like a lot, but you can just practice for about 15-20min whenever you come back from school BUT for 5+ day each week. This totals around 75min - 140min of math study each week without you noticing it a lot. You can increase it to 30+min a day if you want to but consistency must be the priority rather than time. I've seen people making great progress with this method despite initially thinking they're just not made for math. What you DON'T want to do is to leave math practice to the weekend only. Even if you study math for 3 hours in the weekend it is not going to be as beneficial. I personally was able to minimise my silly mistakes (which are incredibly common!!) by doing math consistently even if it was for a short period of time.
Regarding resources, you can try Smartermath questions which are often accumulated past (up to 2000) HSC questions based on topic. Your teacher may provide those, or you can find some online on websites like Studocu. These can be helpful if you want to do targeted practice only on specific topics to learn them better. You can also try
https://hscmathsbytopic.firsteducation.com.au to get HSC math questions by topic. The THSC website also has quite a lot of past trial exams from different schools with solution which you can try. But make sure that you can do textbook questions first before trying HSC and trial questions. Textbooks like Cambridge Year 11 and 12 have classified difficulties such as "foundation", "development" and "Challenge". If you can do the foundation and development difficulties, you can attempt exam questions.
But regardless of the marks you've got in the exams, DO NOT put self-limiting labels on yourself because our brain is capable of developing many skills. It just needs some time.
Good luck!