550-600 is definitely reachable by you. However, the Veritas program, and more specifically, the class that you are in may not be best suited for your goal. Most of these programs are geared towards people who want 700+
My suggestion is that you do one of the following:
1)Study on your own and get down the basics before continuing with the Veritas program
2)Ask if you can change classes where your classmates have lower diagnostic scores. This might not be as helpful if the instructor just plows through the material and doesn't much care for student feedback.
3)Eschew the entire program altogether and try a Princeton Review course, which is more basic.
OR
4)If at all possible, study on your own at your own pace.