Thanks for posting. You are pretty young at this time compared with the average b-school applicants, BUT you have a lot of experience at a young age. Not sure when you graduated, maybe the 2-3 years of experiences you list at first are your post-undergrad experiences? Which are generally the main focus when you apply to b-school.
The volunteering experience is extremely compelling; not only does it show how much you have gone above and beyond to help community needs, but you've also been able to gain various management experiences through this as well, it sounds. So while you have less experience than average overall, you can speak to the fact that you've experienced a lot in a shorter amount of time and that you have a lot to bring to a b-school class.
The biggest missing piece at this point for me is the WHY... why do you want an MBA? What are your career goals? What do you need from the MBA to reach those goals? The schools will DEFINITELY want to hear this and it should be genuine, convincing, compelling... if you can nail that, and particularly relate your prior experiences to your future goals in some way, you should have a decent shot at your schools you listed with a GMAT of 650+. Good luck to you, keep us posted!
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