If don’t have formal volunteer experience, have you informally helped others or do you have a strong personal story that can help demonstrate your character and/or passions? It is not critical to have these types of experiences, but they are helpful to differentiate you from others with similar backgrounds/career goals, particularly since so many applicants want to go into consulting. Also, business schools want applicants who will become active members of their business school community so give a feel for how you would do that. You can get involved in volunteer experience now. Just make sure it is something that you passionate about and you are actively involved in so it is genuine and not just for your resume. Can you do something with literacy since this is an interest of yours?
For your work experience, you are just under the average years of work experience for these schools. It’s great that you have a promotion (or two). Can you demonstrate leadership and maturity from your experiences? I would suggest that you better define your career goals so can clearly demonstrate what transferable skills you have already and why you need an MBA (particularly now) to get where you want to go. If you feel that you are light in this area, than have a clear plan for what you will achieve over the next year to strengthen your application for the following year.