Hi Ayeh,
Out of interest, do you have a Careers/Guidance counselor at your school? If so, they would probably be the best person to ask. Otherwise, a teacher could also work.
In any case, here are my two cents:
I'm not sure of your prior experience, however learning a language can be very difficult. Unless you are quite competent already, it is not a terrific idea to begin in year 12, due to the competitiveness of the cohort, as well as the time it takes to develop your practical skills/vocab.
I do not know your history with economics, nor health, however, you shouldn't switch subjects off of a whim. Instead, take some time to really think about which subject you will do best in.
Overall, I can offer 2 pieces of advice.
If you are struggling in a subject, seek extra help from a teacher. I'm sure that (most of them) will be happy to help.
Similarly, for subject selections, choose the ones that you are the most passionate about (unless they are prerequisites), because you will therefore be more motivated to study.
Hope this helps
