Hi srtas,
First off, a 660 is a strong Score, so it could be enough to get you into your first-choice School. As such, a retest might not be necessary. You're ultimately asking Admissions questions though, so you would likely find it beneficial to speak with an Admissions Expert about your overall profile. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/If you do choose to retest though, then we have to examine your prior studies. It would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) What were your Quant and Verbal Scaled Scores for your Official 660?
2) How long have you studied? How many hours do you typically study each week?
3) What study materials have you used so far?
4) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
GMAT assassins aren't born, they're made,
Rich