I won't tell you whether you will do fine on the DAT or not...I don't think anyone can really predict what weird things will happen, how much you will study, how hard you will study, how nervous you get, or if you just suddenly peak on test day with scores of 27+
All I will say is that the topscore and DAT achiever CDs seemed to get harder and harder as I went. Even though I had learned more, it seemed like my scores stayed the same or lessened...and part of it was just fatigue cause I'm just so tired of the DAT and prepping for it right now that if I ran into some Vietnamese guy named Dat on the street, I might just beat the living crap out of him with my Kaplan book.
Anyway...Topscore isn't easy, and if you scored those scores as a diagnostic before you started studying, then that's porbably not bad. give yourself a couple weeks to study and then test again, and see how you feel. Remember that you have up to 48 hours prior to test day to reschedule.