You stated that you are bushing your teeth two to three times a day. That you also floss at least two times a day and you are useing Listerine mouthwash after brushing, as well as seeing your dentist for the required cleaning.
I think you are covering all your bases very well. There is not much more you can do. I know that there are some mouthwash that will indicate that they have gingivitis protection maybe look for that. I have hear of the Oragel Mouthwash. My friend uses it sometimes and it does work for minor mouth pain.