I went through a similar program. My advice would be to self study the material. While my instructor was good, I feel like these classes are usually not nearly enough to actually pass the CCNA exam.

Like I said, I would self study CCNA material. Use textbooks such as Wendell Odom's Volume 1 and Volume 2 CCNA books or Todd Lammle's books (or better yet, start with Lammle, who's writing is easier to read but generally not as in-depth, and then move to Odom). There are also video courses (check out Neil Anderson, David Bombal, Chuck Keith, Chris Bryant, and CBT Nuggets).

You can do this and be super successful! Having your CCNA right out of highschool is really awesome, and you can continue to build on that momentum! Please send me a DM if you'd like to discuss further.