Too late for your interview; hope it all went well.
If you don't get a NROTC scholarship from the start (and there's lots of folks that don't) you CAN pick one up later. Go to school, bust your butt, join NROTC as a frosh, and make a good impression on your advisor and CO. As long as your GPA is competitive (for tech majors, about 3.0+, for bull majors, 3.2+) you should be good. I'd also probably take calculus during your first semester, if you feel confident about your math skills. Otherwise, register for the pre-calc class and do well. The Navy does look closely at your ability to handle school and particularly science/math/enginerd classes.
Good Luck!
JT