only you can know how you guys are when you are toghether. If you are having this many second thoughts about it then you really need to search within yourself. How does he treat you when you are visiting him?? has he ever talked about family in the US?
I dont think that he has any legal rights to the child if he stays in Jamaica. To his defense, is he maybe just stressed out about the whole process?? anxious about starting a new life in a few weeks and so on..... these are all things you need to consider. Nobody else can decide that for you.
I wish you good luck