I had the same issue in year 12. I decided I'd try stick it out for the first year, see how I got on and then move onto something else if I thought it was appropriate once I had an idea of how well I was doing at the end of year 12. I ended up actually enjoying my courses once I got into a proper study routine and began to understand that it's a big step up from Y11/everyone is in the same boat. You get into the swing of things eventually, just so long as you're committed to it (i.e. willing to not only do your homework but extra reading from the start, etc.).