I AGREE!! If you enjoy Chem more 100% keep it because you're never gonna force yourself to do Bio homework etc if you hate it.
I struggled with Prelim Chem concepts too but my friends who still do Chem now said for some reason they become more understandable in Year 12.
With the effort you've...
Sure they're not as relevant as the current syllabus but the alignment changes every year irrespective of the syllabus so it's still interesting to look at.
Just start doing past papers or sections of past papers- particularly for maths and english to get a feel for what the exams will be like. You have so much time though you're so fine
Sometimes private tutoring is more effective, I had a really good private tutor who I found on Facebook for year 11 chem- he was AMAZING and helped me get to 2nd rank despite being genuinely rubbish at the subject.
But it depends on the person and at institutions like those it's more...
Good luck to you too. Since you've spent all this time on bored of studies whilst I've been studying for tomorrow's trial, you'll certainly need more luck than me :). Enjoy your restless sleep ;)