Your home school is obviously a target, and hopefully one of the faculty you've worked with will provide a dentist letter for you. Your shadowing is at the bare minimum but isn't a real problem. PAT 18 is low but not "very low", but you might get a couple of waitlists because of it if you don't find out how schools on your list factor PAT in their selection criteria.
I think given the description, you can describe TA as non-clinical volunteering but not community service. Aside from food pantry work, what else have you done that would fall under community service?