It's too late to add any more schools to your AMCAS now.
The MSAR (Medical School Admissions Requirements book) show these stats for IU for IN-STATE applicants:
Applicants: 531
Interviewed: 460
Entrants: 254 (BUT keep in mind, the ACCEPTED number can be even higher!)
According to these stats, you have well over a 50% chance if you were interviewed...meaning that if this were a poker match, I'd advise you to go all in and let the cards fall as they may.
I hear of a lot of people who get in by being persistent, by calling the dean of admissions, by writing a letter of intent (specifically stating that you would DEFINITELY attend their school if you were accepted), and whatever other tricks you may have down your sleeve. Point is, I would seriously envy someone who applied to only 2 schools and spent less than a hundred bucks on this dreadful application process (I spent about ten times that much on my apps🙂...and got in in the end.