If your attending an American Private school it will have a US GPA system. If it doesn’t then you will need to check if its accredited (If not accredited will be an issue). The fact that you don’t have AP or IB will go against you especially if your competing with GEM schools, American School of Dubai and other American schools. Unlike the US they will not look at your school ranking but will compare you to your peers who are applying to these schools your looking at.
Remember American School of Dubai is considered by more universities is the “US sanctioned school’ so they will get the advantage in admissions