I tried to brew Yooper's Oatmeal Stout which went fine until the fermentation process. The batch came through the brewing process with an OG 1.056, a little high but I also only collected 4.5g on a 5.0g batch. I pitched rehydrated US-05, as I always do, but this time I added yeast nutrient and energizer to my wort. I did this because I had leftovers from a batch of Skeeter Pee and figured it wouldn't hurt. After two weeks I checked the gravity of the Oatmeal Stout and it read 1.032. There was no signs of krausen so I checked my hydrometer in water to confirm it was reading 1.000, and it was. I resealed the fermenter and gave it a gentle swirl and did that once to twice a day for two more weeks. I checked the gravity again, 1.032 giving my an abv of 3.2%. Since the FG was stable for 2 weeks I went ahead and bottled the batch but I am very dissapointed Beersmith calculates my efficiency to be 63%, I plan for 65%, and my attenuation to be 41.5%, which is horrible. I mashed at 156F so i did expect to extract some non-fermentables but not quite this much. What caused this horrible experience and would you even let the beer carbonate?