Well double check your hydrometer, to make sure you are reading it right, but there's nothing there that stands out terribly. That is certainly a quick fermentation for sure, but not impossible. Test your hydrometer with water, if you use distilled it should read 1.000 and tap or anything else should be within a very small margin. If the readings are right then your brew just fermented very quickly, and then when you added the sugar water, not sure how much sugar was involved, but it looks like the yeast ate that right up too.
What kind of yeast did you use?