Your cGPA is more or less fine. Boost your sGPA as much as humanly possible in the time you have left in UG. If you're scoring 510-513 on the practice tests, Id go ahead and take it now; an early application is pretty important--a 518+ though is never a sure thing regardless of how much you study.
A post bacc is a good option if you need to reapply, but depending on your final GPAs, MCAT, and overall application (ECs, PS, recs, etc) it may not be necessary/likely. Run your school list by the folks in WAMC when you do start putting that together, too.