The people I talked to about the program made it sound like the NAPT test was hard, the hardest tests they have ever taken.
Of course, many of the people probably only had the benefit of high school.
If the NAPT is anything in content like the previous version, the NFQT, it was not difficult. The NFQT was multiple choice and easy to grade for the enlisted classifiers (the "job counselors" at MEPS).
My inclination would be to advise you to forget about your score. It's one of those things that (almost) everyone remembers and lots of people will want to compare.
Just apply those study habits you developed in college. I remember the top student in my section 11 NPS class (when the sections were grouped into people with similar aptitudes). He only put in enough time to complete the homework, never stayed to study (except for the last week when everyone was given mandatory study hours), and always got the top score in the section. After NPS, the next time I met him was out in the fleet. He was still a second class (which he might have gotten by reenlisting STAR or may have been demoted to). I had not gotten second class by automatic or command advancement, but had still been a first class for at least a couple of years. Perhaps everything came easy to him and he did not apply himself.
Yes, I thought the "nuke test" was easy and NPS was easy. But part of it is not only learning the material, but learning the Navy way of approaching the material. That will be more evident in the prototype, hands-on, part of the training, where the the person who is used to relying on a good memory can find him or herself in trouble. Nuke school is competitive. I probably logged at least as many voluntary study hours as those in the lowest section and I still could not reach the same level as that top student who did his homework during class and went home to his wife right after school. That's a bit extreme and most successful people have a more balanced approach to life. Just maintain good study habits and turn them into good and effective work habits in the fleet.
So, don't form an impression by your experience with the NAPT and what you've heard from others. There are a lot of smart people in the Navy Nuclear program who have all passed the NAPT, whether or not they thought it was hard. (Yes, to be accurate, some did not have to take the NAPT.)
Just treat NPS as a new and challenging experience!