Hi,
Before I say anything else - let me say this. Keep your chin up! This is a long, difficult process and you've got to stay confident! Like they say, it isn't over until the fat lady sings and that could not be more of the case here! There are a lot of things that go into a great application and a GMAT is just one (albeit important) component! You're going to move your goals forward with a great education, but you've got to believe that too!
I understand your hesitation regarding retaking the GMAT. It's a personal choice and if you're uncomfortable with it, I think you go with your gut. You also have a valid point regarding what this will do to the time you have available to prepare you applications. We start working with our clients in the mid-May to mid-June time frame and if you were busy studying for your GMAT, you would be a little behind.
If you go forward with your applications, your chances increase the moment you go below #10 from a candidacy perspective. The stigma of "top 10" carries with it certain application requirements and thresholds that have a little more wiggle room lower in the ranks. So the moment you start looking in the next 10 - 15 ranked schools, you're in a much better spot. In this case, your candidacy is different than a lot (not all, but a lot) of your candidacy pool so that will help significantly.
What it will come down to is how do you convey your value beyond metrics. How do you make a case for each of these MBA programs to invest in you because of what you bring to the table. Your story must be compelling and unique - without this, despite the fact that your metrics are in line with these programs, you may still not get the results you desire.
When it comes to selecting programs and the associated ranks, there's a much larger discussion around that to determine not only what is a stretch versus realistic, but also which match you best and to which you match best.
With your score and your experiences and your overall profile, you've got a solid fighting chance in the 11 - 25 range. You may even have a chance at the lower end of the Top 10 but without knowing your entire profile in detail I'm not comfortable making that assertion.
Does that help?
Bhavik