Though you have a low GPA, it sounds like your extracurriculars are awesome which is one thing that you can really play up in your postbac apps. Make sure that you're applying to postbacs that are application enhancers instead of career changers though, otherwise you'll immediately be rejected from those programs since you've taken most of the premed course requirements. I would also make sure that you thoroughly explain in your personal statement why your GPA is so low and the steps that you've been taking to fix that problem.
As for your career decision, DO programs are typically much easier to get into than MD programs. Their entry requirements are less strict and they're more forgiving with academic hiccups versus traditional med school.
Hope this helps!
