I would agree the overall evidence is that Turnera ulmifolia is wide spread in Florida, it is part of a complex with variations, and is most likely to be that plant. If it isn't, nobody will know unless they send someone around to confiscate your plants to do scientific evaluation on them.
These 'queries' can be very educational!
Of course, without taking parts of your plant and comparing them with the identifying features as shown on
this site there will always be a small element of doubt, and there is a possibility it's a hybrid. My mind tells me that is a real possibility due to the hybrid nature of it, hybrids are generally chosen for uniformity of germination, their good looks and flower power.
