There are odd quirks even in the US. In some states, you can get an out-of-state rx filled exactly ONCE, and then any remaining refills are voided out and the rx cancelled. Best bet, if you are on a medical plan, is to get their response in writing. And then check with the specific countries that you will be visiting. Ask the US embassy, consul, whatever they have there, and ask the locals. There will probably be a local pharmacy in each location that has some kind of internet presence, try to ask directly.
If all else fails, "your" home pharmacy may be able to express them to you, either by courier or US Mail if you plan ahead for mail drops, and leave them with the right packaging.
That assumes there is a counter for the stuff to be available over
When my wife needed medicine when we were in Harbour Island we lucked out and they had it at the island clinic, but if that hadn't worked out I was going to fly back to Florida to get it. 4 hours round trip X 12 gallons/hr X $5.00 gallon for gas = expensive errand!
If you get to the Bahamas and find you can not get your meds over the counter or with your scrip then I would go to Planet Drugs which is a reputable Canadian online pharmacy and order direct from them. Fax them your scrip. They will post to you in the Bahamas.