Sugar doesn't suspend the yeast eats the sugar.
Take a gravity reading after you cooled wort is in the fermenter at pitching temperature, this is your original gravity reading. As fermentation goes on the yeast eats sugar and the gravity readings drop.
Couple of things you could look at, human error, or an inaccurate hydrometer. Also the temperature you sample at will effect your reading.
Can you check your hydrometer on room temperature water, it should read zero.