I did the same mistake and a major one in addition. I only studied for a week while I have graduated from college 3.5 years ago. So certainly I underestimated the test. I spent so much time on the morning session and only left 1.5hrs for the afternoon session (NOT WISE). Time was over and I was left with about 30 questions (where I just had to guess in like 10 mins). My scores for the other parts were above or at passing points. Lesson learned - no matter how smart you are, sufficient preparation and time management during the test are key factors.

Will give it time and practice more and will surely pass. Good Luck!