You can do a "proctored" test to go back to USA. I plan to use the Binax NOW test in July when I return to the US. There are many places on island where you can get tested, and the prices range widely. Following is a link to some of the places where you can be tested. I have used Medwork in Simpson Bay twice. But the proctored testing is less expensive and you can do it in your room, which is why that's what I will be doing this next trip.

LINK to EHAS testing