Thanks for sharing your profile.
I can understand your discomfort with sharing your medical condition with the adcom, but to be honest, as far as admissions goes, it will be best if you disclose the situation in an optional statement. If there's a reasonable explanation for having a low GPA, the adcoms are usually forgiving. Ultimately, that's up to you though, as it's a very personal choice.
It's good that you are taking supplemental courses. Your work experience sounds strong, and you're pretty active in the community, so that is good. Columbia may be a stretch, but depending how the GMAT goes, you could apply. More realistically I think Duke and UCLA are great targets. Rice and Austin are also good targets and hopefully safer options. I think it's a decent list, especially if you disclose your medical issue in your application and score well on the GMAT.
If you can take on any extracurricular activities in the meantime, that could help too. Marathon, bike race... whatever you're passionate about - set a challenge for yourself and go after it!
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