Your current number of GMAT attempts are exactly the number of attempts I made before finally being able to score a 740 on the fourth attempt. However, my strategy was a little different from yours and you may wanna see whether it could benefit you. Whether you should apply to schools with this GMAT score depends on the average score at the schools you'll applying to. If the average score is more than 660 ,it makes sense to retake the GMAT ,otherwise you should be fine with the current score. As you said that you couldn't sleep the night before the exam, I think that could also have played a spoilsport and brought your score down. I'd suggest that you relax for the next couple of days ,think with a cool head,research more on the strategy here on this forum and then when you become confident that you have the right strategy and approach to take on the GMAT, then you can kick start your preparation.