If your clothing selection is limited, it is certainly acceptable for you to wear the same clothes often. In general, you probably should not wear shorts to your school. Cut-offs, raggedy shorts, skimpy tops, and very short skirts are definitely out. Leave your facial jewelry at home. Many schools are especially concerned about footwear, for safety reasons.
Open shoes can pose problems for children.
Some schools believe that there should not be a double standard for the teachers and the students. Therefore, if children are asked not to wear open shoes, teachers should not wear them either. Observe what kind of shoes the teachers in your school wear and do the same. Wear clothing that looks professional. It will tend to make you more accepted by teachers and more respected by students.