Wind's effect on light rider?
This is pretty simple. All things being equal, aerodynamic drag is a function of the relative wind velocity squared. Doubling the effective wind speed increases the drag force by a factor of four. Head winds could easily account for the loss in speed you are experiencing. Your body weight isn't a factor in dealing with head winds. Indeed if you are relative small, your drag will be lower than a larger rider. Weight is much more of a factor on hills, but in Florida that shouldn't be much of an issue.