According to the information I care about, I suggest you find a good intermediary, because they are more experienced, can fill out the application form for you beautifully, and will train and tell you many questions when facing the examiner. And you just have to think about TOEFL or elegance yourself.

Going abroad in high school or university is the best opportunity! Because when you graduate, there will be no other opportunities for you to experience life abroad for a long time. Unless you have a legitimate reason such as a job. So your situation is not special at all.

Freshmen in China can transfer out, but only to the same major.