Thats a big bummer because not only do you get penalized for getting those problems wrong, but there is an extra penalty for leaving the problems blank. It would have been better to even guess and get all 3 wrong. You SAT score will not come into play, and if you're considering an M7 score, they are probably going to want to see 80% or above in your Quant. Unfortunately, it looks like a retake may be in store for you. With getting those 2 or 3 of those last problems right you could have score 750+. Sry, but it sounds like you have all the knowledge, now you need the timing.
A 720 is an excellent score, but with such a lopsided breakdown with a low quant, it's going to raise a red flag questioning your quant ability. The only way I would consider not retaking is if you can easily show that you are strong in quant including in your essays, letters of rec, job, CFA, CPA, and math classes in college.
New to the GMAT Club? <START HERE>
My GMAT and BSchool Tips: