thats very good. You seem to have a lot of leadership and responsibility type of experience which is always a plus. Your GPA and MCAT is very good as well. You have shown maturity by enrolling into a post-bacc program. Talk about how you did not have time away from school and work to put into more extracurricular activities. I dont think it should be a big thing as your other stuff looks really good.

good luck and dont mess up the interview. Follow the interview questions that are posted on this forum and you should be a strong candidate. Myself and everyone that I know and have talked to have gotten pretty much the exact same questions.