Why Harvard? It is one of the most difficult universities to get into in the world. You must have top grades and test scores, extremely accomplished extracurriculars, and outstanding letters of recommendation from teachers that have taught you. Do you have all these requirements?
Harvard does not accept by department. Whoever told you this has no idea how Harvard works. SAT subject tests are meant to be taken in high school, not after you graduate.
You cannot apply as a freshman if you have been to university before. It doesn’t matter if you only went there to please your parents.
I am going to be blunt. Your English skills are not good enough for Harvard or for other selective universities in the US. While most of your sentences are understandable, they are not correct English. If you are going to study in the US at a selective university like Harvard, your English skills must be much better.