From what I've gathered recently:
1. All courses taken at any university will be calculated for your GPA. You will have to report courses and grade work from all three universities you attended.
2. Retaking classes will not replace your GPA if you are looking at MD programs (AMCAS).
3. You threw around a lot of GPAs in your first and latest post. I think I am kind of confused. Are you saying your cumulative (all courses at all universities) GPA is ~3.2? You mentioned your undergrad gpa is 2.97, which is what everyone assumed above.
If your overall GPA is 2.97, you will have lots of work to do to raise this above 3.0 to first get past initial screening. Then you must prove to med schools you can handle hard science coursework and an SMP (as suggested by Stratego above), is a great way to do this, but obviously very risky and tough. You need to compete against med students, which is not easy. From what I've gathered, if you screw up an SMP you further damage your chances to get into an MD or DO program.
If your GPA is actually around ~3.2 (and science GPA?), then you still have work to do. It seems like your trend became worse, as your GPA at the final undergrad institution was 2.97, a big decline over your 6 year college streak. Also, you have switched universities plenty of times (I work full time, and this is similar to job hopping, I don't see it as very good). Were there any circumstances for this? E.g. family moved, etc. I think you should start taking coursework to up your GPA a bit and try and study hard for the MCAT (similar to what I'm doing) to nail it. How were your grades in the actual preqreq classes (Gen chem, gen physics, organic, bio)? That would also say a lot.
Regards,
-Medfan.