Too many factors to tell right now. If you kill your MCAT and get your grades up, you likely won't need a post-bacc. However, if you were to graduate with a 504 and get under, say, a 510 on your MCAT, then a post-bacc might be a good idea.
Considering you need more time to get some extracurriculars done, you likely won't be able to adhere to the schedule you've formed.
Kevin W, MCAT Tutor
Med School Tutors