Your choice of major isn’t a factor, given that admissions knows that 65% of students change their major within the first year…especially those with intentions of entering the engineering program. Being pre-med with an international studies major is an interesting combination. I’d suggest a minor in biology or another science.
Your ACT score and grades are very good, so that gives you a high chance. NHS doesn’t mean much, to be honest, since it seems like everyone is a member these days. If you work a lot of hours every week throughout the year, then that will help explain your lack of other extracurriculars.
I encourage you to get a teacher or counselor to read over your essay and make sure it really shines in terms of content. You’ll probably get into Scholars as long as your essay sounds genuine and connects to your interests.