I suggest contacting your insurance company regarding how to proceed. I have heard that every company has different requirements.
First, I needed prescriptions from my doctors for the future prescriptions in 90 day increments. My insurance company (Blue Cross/Blue Shield) required a letter from my former employer stating that I would still be eligible for coverage for the future time period of those prescriptions. Then, the insurer wanted a letter from me stating where I would be and for how long. I sent these letters to BC/BS together. I received a letter back, granting me a "vacation over-ride" for my prescriptions. The letter failed to state that this over-ride was only good for 30 days from the date of the letter. By the time my snail mail was forwarded to me and I received their letter and went to a Walgreen's Pharmacy to fill the prescriptions, the over-ride had expired. I had to request another vacation over-ride, which was mailed to a friend's house in Miami.
I have been generally happy with Walgreen's for filling prescriptions while in different ports in the states, though I have had to come back in a day or two a few times to fulfill the prescription. I don't know of any US-based pharmacy chains with store locations in the Bahamas. I also don't know if mail-order pharmacies, such as Future Scripts, will mail to locations outside the U.S.
Good luck!