It's good to see that you have many of the same problems that I do when shooting sunrises and sunsets. Here in California we didn't have any clouds for almost six months. Without clouds there is little reflection of the sun's light. Here you have a perfectly calm lake to further enhance the sun's work; but without those clouds, you have a vacant sky. Believe me, I know because I have a gazillion sunset shots taken at the local lake with no clouds. My advise: wait until there are some good clouds and head back there for another shot.