Hi. I'm a medicine doctor...recently completed residency in US and went to med school in the US too (MD).
I would say stay in your US degree program. It's always good to have a 4 year college degree...it's a feather in your cap and something to fall back on. You don't say what you mean by "not really great" science grades. Do you mean a 3.0 or a 2.0? It makes a difference. First thing I would do is go and talk with your academic advisor...get advice about how you can get better grades in your science courses. Also, sometimes it's helpful not to take too many hard science classes at the same time (like, don't take organic chem + physics + cell biology all in the same semester like I did in undergrad!). The other thing to keep in mind is these Caribbean schools are there to make money...they will take people, some of whom won't graduate and get a residency. These people borrowed $150k or something to go to med school. What will they do if they can't get residency in the US? They are hosed with no way to pay back those loans.
You don't say if you have a particular interest within medicine. If it's primary care, then also consider physicians assistant or nurse practitioner programs in the US - I am an internist and I know what I'm talking about here...these people are smart and they are laughing all the way to the bank, as they make 80k or so, and do many of the same things a family doc or internal med doc or pediatrician does all day, with less risk of being sued and I would think less job stress. Also, physical therapists can now go for a master's or a doctorate, and they also do well and have an interesting job. I'm not trying ti dissuade anyone from med school, it's just that I think sometimes people don't consider all the alternatives out there. Optometry school is another alternative - tend to people's eyes and basically do a lot of what an ophthalmologist does, excluding eye surgery, It seems like med school is the Holy Grail, but that's not true. There are lots of other medical careers that really in the end aren't all that different, and take a lot less time and money to get there.
