Maybe a few ideas:
-Dinner @ Victoria & Alberts
-rent a boat for the fireworks @ EPCOT
-something silly not romantic - the rehitching ceremony @ Garden Grill - if they still offer it.
-also, just a fluke for us, but a few years ago, we went to Spoodles (@ Boardwalk) to eat, then walked around to Y & BC, we were on the beach as the fireworks @ EPC started, very romantic.
Also, where are you staying, the hotel maybe able to help you. CONGRATULATIONS!!!