considering you have no college bio, and the exam is this close, i highly suggest you watch the 7hrs of videos chad does have posted here for free before your exam. while not complete by any means, you have 2 days. that being said, you show consistency in your target range in your physical sciences & verbals scores, so that's positive. considering your practice scores are all 29+, a 28 is definitely realistic and more than likely. good luck.
http://www.coursesaver.com/videos/MCAT/