What is your recent GPA trend(particularly in sceicne classes) the past 3 semesters or so? If you want to do a DIY post-bacc, it would be best to apply after that's complete. You will be judged by what your GPA is at the time of the application, not by classes you take in the future.
20 schools is fine its just a matter of choosing the right 20.
The EC's look sufficient although I would recommend also trying to get some non clinical volunteering experience.
Also consider Einstein, Saint Louis, Jefferson, Dartmouth, Miami, Cincinnati, Stony Brook, Tufts, U of Iowa amongst others. If you dont have MSAR get it and pay attention to a) % of OOS matriculants a school has b) their 90th percentile MCAT c) 10th percentile sGPA. Also unless you are from Arkansas you didnt list all or any of your state programs on your list; if you have more that arent on your list include them by all means.
If you are looking to cut schools start with South Carolina, Arkansas, Florida Atlantic and USF if you arent from those states. Schools like Rosalind, Rush and VCU tend to interview relatively few who hit 522 on the MCAT unless they have a strong reason to believe those applicants are likely to attend or are a very strong fit for their mission.
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Constructing school lists can be somewhat tricky for an applicant like you because alot of lower tier schools could potentially look at that 522 as low yield but the higher end schools might have bigger issues with the 3.3 sGPA. Still, if you apply broadly I dont see why you cant have a pretty reasonable shot at being successful.