How about you go on with this subject and concurrently start doing the spesh course. Didn't Damo17 do that last year?
Yeah I did but only a little here and there because I found that what was in the course outline for Gen.A was too easy. Like the complex numbers topic was way too easy so I did some from the spesh course and liked it alot. My advice would be as Costargh said go on with Gen.A but also do some questions from the specialist book. Borrow it from your school library. Just do some questions from there as an extension to what you would be doing in class and it would then aid in your decision whether or not to continue on to specialist next year.
You say you don't have time to do specialist but I don't mean do the whole course, I mean just read over a little bit from the specialist book and do a few questions whenever you have some time to do it to extend your knowledge on the current topic you are studying and hopefully that would be more interesting. However I would only say to do this on topics you feel you know well as it would be useless to go on without understanding the Gen.A theory on that topic.
You say you hate trig but the trig at methods/Specialist level is very different from yr 11. Maybe you could learn reciprocal trig graphs and inverse trig graphs. Or maybe study some trig identities from the spesh book. That might get you interested. Maybe ask your teacher for some extra questions that would challenge you. There are plenty of resources on here for maths that you could have a look at and see if it interests you.
And as True Tears said, Gen.A is really only meant to roughly introduce some of the topics covered in spesh in brief. But for some people it can be too basic and become rather boring. And as you said it hasn't been that long into the year so you will cover alot more topics that you might like.
But it all comes down to whether you have a passion/interest in maths and are willing to go onto spesh. And also your possible career paths.
Hope this helps.

P.S. I didn't mean this to become a sort of essay.