Hi danpark91.
My best guess is that the test exposed some weak areas in your quant skill set that you were not aware are there.
Meanwhile, it's likely that part of the reason that you scored higher on practice tests than you did on the real thing was that questions that you saw on the practice tests were similar to questions that you saw during your prep, whereas some questions that you saw on the actual GMAT were somehow different from the ones that you saw during your prep.
So, there are two takeaways.
The first takeaway is that, to hit your score goal, you have to find and address weaknesses in your quant knowledge and skill set. Doing so will take carefully considering the different areas of quant to determine which ones you aren't comfortable with. Once you have found such weak areas, you have to fill in gaps in your knowledge, and then do, not a few questions of each type, but dozens of questions of each type, until you have mastered answering questions of types with which you are not that comfortable answering now.
So, for instance, if you were to decide that you aren't the comfortable with coordinate geometry questions, you would fill in gaps in your knowledge of how to handle coordinate geometry when it appears in GMAT questions, and then do dozens of coordinate geometry practice questions.
The second takeaway is that you have to develop your quant skills in a way such that you will be able to answer a greater variety of questions, as in, you can't be limited to being ready to answer questions in patterns that you have seen before. Developing those skills is another reason to answer many many more quant questions of various styles. You have to become ready for anything that comes your way.