Honestly, probably not SGU. Their average is around a 3.4/26 these days, however most students are not neatly within this range. Anecdotally, it seems most students at SGU fall into 3 categories:
1) Impatient students; plenty of kids heading to SGU are feeling the effects of the increased competition for getting into med school here in the US. I've met people who have, at least claimed, to have competitive GPAs and MCAT scores (>/=3.5, >/=29). Some of them were waitlisted and didn't want to reapply, some were just outright rejected. I think this is the minority, but certainly a growing minority.
2) Low MCAT; this is also a form of impatience. The reason SGUs average GPA is pretty decent (3.4 or so) is because a lot of 3.6+ students decide to go to SGU after they get killed by the MCAT. If you have a 3.6 or so, SGU will pretty much overlook your MCAT. They aren't desperate for students, though, so you'd still want to have over a 22 or so to get in with a good GPA.
3) Low GPA; along with low MCAT applicants, this is probably another popular reason for going there. When I say low, I am talking around 3.0-3.1. Usually students this low seem to have really competitive MCAT scores (30+s).
Now, others will probably chime in about how they had a friend that got in with a 2.4/20. These people are outliers, and probably got in back in the day. SGU is definitely a good school if you want to go to the Caribbean, but as I mentioned earlier, they aren't hard-pressed for quality applicants. Pre-meds falling into the aforementioned 3 categories usually pick SGU as their first-choice. So in all honesty, I do not think you'll get into SGU.
AUC and Saba are also quality schools, but without a really awesome MCAT (over 30, definitely), I don't see them accepting you either. They will have no troubles filling their few hundred seats per trimester with students that have >3.0, >24 MCAT scores, which most schools apparently feel correlates with success in med school. By accepting someone who they feel has a good chance of flunking out, they are going to lose revenue that they would have had if the student had stayed in the curriculum. Economically, it makes sense to accept stronger students.
I do think, however, if you can get a 30 on your MCAT, you can get into Ross. It's a good school, no doubt, and gets you where you want to go. Since they were bought by DeVry, though, they have been hitting some rough spots. Their clinical affiliations are a nightmare these days, so I've been told. Classes are getting bigger, I believe. I think Ross' all-encompassing drive for profit is convincing them to accept students with lower GPAs and MCAT scores than the other established Caribbean schools.
Does this mean Ross is any less of a good school? Not at all. Ross produces doctors of high quality every year. There is no hand-holding, however; they will accept you even if your stats are crap, but if you flunk out, they could care less. Ross is a beacon of hope for those who screwed up or goofed around during the first couple of years of college, but soon realized their potential and got their act together. Ross gives those students a chance. If this is not you, and you maintained a <3.0 consistently over 4 years and have not done an overhaul of the way you learn and study, Ross might still take you; but you will probably not leave with a Ross diploma. Just a lot of debt.
Think long and hard about why you did so poorly in undergrad. Also, it's disturbing that just because you didn't get into pharm school that you want to go to med school now. Medicine is a backup now? Be careful; this is something that will encompass your life completely if you were to get into med school. You will work a lot of hours for many years, so you better love it. Whether you like it or not, medicine will define who you are for some time. I think going into the field because you couldn't get into a pharmacy school is a setup for disaster.
Take some time off, take some science classes to try and boost your GPA, and if after the next couple of semesters or so you can get all A's, kill the MCAT, and still love medicine after shadowing and volunteering, apply to some schools. Best of luck.