Thanks for the brief summary. Keep in mind that top schools are not just evaluating you based on your GMAT score. They also evaluate your professional experience, extracurricular activities, community involvement, character, and leadership profile. Looking across and within these dimensions, I'd say you may wish to consider other schools for your list. Let's break this down:
Academics: a 720 GMAT is a solid score - well done. The difference between this and a 750 or above is a marginal difference - it shouldn't make or break your application. Your GPA is slightly low. All in all, I'd say your academic profile is competitive for these schools, but that your scores don't separate you from the pile in any way. This means there is more pressure on 'rocking' the other dimensions, too.
Professional: it's very good that you've transitioned from a technical role to a business role at Deloitte. However, I'm not seeing a lot of evidence of professional leadership -- these are the types of stories you are going to want to focus on (times when you've led teams/projects, taken initiative to improve firm performance, etc.) With only 6 months in this role thus far, it will be difficult to show the same degree of leadership as your peers who are applying. Your professional experience is good, but it does not stand out.
Community: I did not see any mention of community leadership activities.
Extracurricular: I did not see any mention of extracurricular activities/leadership.
Schools like HBS and GSB are seeking true self-starter - those that not only create and seize opportunities for themselves, but do the same for others. They are also seeking multi-dimensional candidates - those that excel not just academically and professionally, but who engage actively in their communities and their passions. I'm not seeing must of that in your profile, so I would really recommend that rather than retaking the GMAT, you refocus your energies on improving your leadership and non-work profile. Perhaps you can wait a year, work to improve those dimensions and then apply to some top schools. Alternatively, if you must apply this year, I would target less competitive schools such as University of Michigan, Darden, UCLA, etc.
I hope this is helpful! Best of luck.
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