Would I study in USA, if I my test results not so high and I have just 15 hour volunteering?

Answered

So as 90% of American schools are test-optional an SAT score doesn't really matter. Your IELTS may need to improve a bit as if I recall a 7 is typically the minimum score at most universities. You can likely get accepted at most public schools in the US but at selective schools in the US like ivies MIT UCLA Stanford et cetera you will not be admitted 99.9% of the time due to lack of extracurriculars. But there is nothing stopping you to study in America besides your IELTS score along with paperwork/personal circumstances (visas/financial assistance et cetera).

Hope this helps!