Each college and university sets its own policy about which forms you need to file, so you need to tell each one that you are a US applicant who has been educated abroad. There are scads of students in your situation. Don’t be surprised if each college/university tells you something different. Just do whatever A asks for A, and whatever B asks for B, and you should be fine.
You are eligible for federally determined financial aid, so be sure to file the FAFSA. You also might be eligible for some financial aid from the state where you live, but the rules vary significantly from one state to another so you have to investigate.
Because you were educated abroad, your academic records will need to be evaluated by an admissions officer who is familiar with the educational system that you come from. Usually that will be someone in the international admissions office. So yes, some colleges and universities might require you to file some of the same paperwork that a true international student would have to.
If the language school you attended is not part of a college or university, exists solely to provide language instruction, and does not award academic credits that would apply toward a university-level degree in that country, then you have no potentially transferable credits, and you are not likely to be considered a transfer applicant. When you discuss your language studies, you need to make that clear to the admissions office. In that case, it should be treated as equivalent to the type of non-credit intensive English course that many colleges and universities offer (or that are run by other organizations on or near college campuses) for the purpose of getting international students ready to take academic courses in the US. They may want to see the school records, or they might not, so be prepared to provide official copies of those records.
If the language school you attended awards credits that can be used toward a university-level degree, then you may have enough potentially transferable credits in order to be required to apply as a transfer applicant. Again, the number of credits that will make you a transfer applicant varies wildly from one college/university to another, so you do have to ask each of them separately.
Depending on the number of A levels and your scores on those exams, some colleges and universities in the US will not require that you take the ACT or SAT, and some will award credit or advanced standing. When you communicate with the admissions offices, investigate their policies about A levels.
Wishing you all the best!