Applying in September + 28 MCAT = the kiss of death
I beg to differ. I was complete at the end of October. Low GPA, average MCAT, interviewed December to March. Autism Spectrum Disorder (worked on it for years though). Got in somewhere.
Possibilities:
1) interview skills. Maybe people were put off by your "gung-ho" attitude? One of the feedbacks I got from a school I was rejected at was that I appeared "too aggressive" and "lacked interpersonal skills." (The other three schools ranked me very well in interpersonal skills, oddly enough). Did you appear arrogant or douchey? Maybe try to be more calm and collected?
2) bad LOR. Many (if not most) schools only review LORs post-interview. You may have had a really poor or unremarkable LOR. Maybe your PI secretly dislikes you or something? Something to think about.
3) was it a state school? One of the state schools I interviewed at has a policy of only taking a small number of OOS. They told me I was great but that they can only accept 2 OOS and even then they have to go to the bottom of the wait list. I'm no purple unicorn, so I understood why I wasn't chosen. If you had too many state schools on your interview list that may have been why.
4) you may have not sounded interesting enough. Maybe your experiences sounded too cookie-cutter? There is a happy medium between passionate and naive that must be found in order to sound compelling and mature to interviewers. It also helps to focus on how you learned from your experiences.
5) A combination of small factors with your MCAT being the last nail in the coffin.
All the best! I'm sure you'll bounce back next time. I hope you retook the MCAT. Maybe scoring higher than 28 can correct or compensate for other weaknesses you may not be able to control or are not aware of.
Most importantly, seek feedback from all the schools you interviewed at. With the exception of the school I got into, all schools I interviewed at gave me feedback happily. (My weakness was different at every school: one found me aggressive, likely figured out my ASD; one said I didn't answer their teamwork questions the way they wanted - I have little experience working in teams, which could account for this review; and the third was the state school that only wait lists the top two OOS). Please, do seek feedback, and be receptive to it.