This is just my personal opinion...but if you don't start improving on your GC and OC at the very least (improving as in getting at least 21+) you might want to reschedule.
I'm saying this because for my first practice tests, I took achiever got around 17s for the sciences, but when I took qvault I started getting 21-26. Same with PAT, on achiever I got around 17-18 but with CDP I am now getting 22-25.
Furthermore, many people have breakdowns with qvault and CDP practice scores that represented their real DAT scores very well, whereas if you had used achiever, it seemed like a 5-6 point jump.
My point is that....personally I think the resources you are using are on the easy side of the "practice material" spectrum and that if you aren't feeling comfortable with them, you probably are not ready.
That being said, I think you still have a shot at getting around a 19-20 if you have 6 days left to study. Give it 3 more days before you absolutely have to reschedule and see if your practice scores improve, which is a high possibility because for OC and GC at least, there is only so much material you can learn before you start mastering them.
I apologize if I was harsh, but it's my honest opinion. I am taking the test exactly a week from today and if I was in your situation, this is what I would tell myself. Just keep doing what you've been doing with qvault and CDP for the next 3 days and if nothing improves, pay the 25 bucks for a later date, it will be way better than paying another 360 and also having to re-study for another 3 months.
