What kinds of mistakes are you making on practice tests? Do you run out of time, not know how to set the problem up, lack of knowledge, etc.? Is it just test anxiety?
Be confident in yourself! I took my DAT a few weeks ago and the night before I thought about rescheduling because I did not feel ready. I also knew that I would not be able to take the DAT soon with a new semester starting so with the encouragement of my family I took the DAT. I ended up getting a 21 AA. Go with what you are feeing but if you do decide to take it be confident! You will do great! Good luck!