I recently brewed the Brewer's Best Milk Stout, which uses LME plus lactose and maltodextrin. The original gravity was 1.060, which is within the specs for offered in the instructions. Now after about 1 month in secondary, the beer is is holding steady at 1.030, which is apparently too high (specs indicate 1.020 - 1.024). I'm nervous to bottle in case they will explode.
I tried adding some dry ale yeast (Safale US-05) to try and kick the fermentation on, and even added a little heat with a brief water bath, but after one week there is no change. Furthermore, the room im fermenting in ranges from about 65-70 degrees, so it seems unlikely to have become stuck from low temperature. Also, the beer tastes fine right now, but I don't have the experience to tell whether it's "too sweet".
Two potential issues come to mind. First, I spaced out and failed to add the lactose and maltodextrin to the boil -- they were added just before racking into the primary. Perhaps these non-fermentables didn't see as much conversion to fermentables as they might have? Second, I may not have used a temperature conversion for the original gravity, so perhaps the OG was actually higher than 1.060, and the 1.030 really is indicating a greater amount of non-fermentable sugar than I am expecting?
What should I do? I'm tempted to just bottle it, since my hunch is that the high FG indicates a lot of non-fermentables, but perhaps I should try adding some more yeast of some kind? What kind?