Richie--I assume by 'direct', you mean 'non-stop', although it is not the same thing.

In any event, the only non-stop from Central Florida is with Frontier from Orlando. However, it is only seasonal and only on Saturday.

Other than that, your options from Florida in general are as follows:

AA nonstop from Miami--usually daily
Spirit nonstop from Ft Lauderdale--depends on the season, but they are upping number of flights per week, supposedly going to daily flights as of some time in November.
Frontier WAS flying from south Florida nonstop, but not sure whether they currently are or not.

Delta has connecting flights from Tampa and Orlando, connecting through Atlanta to SXM.

AA has connecting flights from several places in Florida to the Miami flight (or to Charlotte or Phlly, etc), but you need to check the total time for the flight, and figure in the hazards of a connecting flight, to see if it's worth your while. We look at the total time allotted with a connection within Florida, considering we have to drive 1.5 hours to either Tampa or Orlando, and have decided that for us, connections within Florida do not make sense. For US, personally, we normally drive 3.5 hours one way for the non stop AA flight from Miami. That said, I like Delta's planes and their overall experience better, BUT I prefer to do a non stop, all other things being equal. Your mileage may vary.