What kind of soil have you used and have you added fertilizer of any kind? This is the only plant, these carnivorous plants that are able to get the chemistry with which to survive, without a lot of the chemistry most plants that only do photosynthesis need to have to make their own food to survive.
Yet even these plants need a tiny bit of chemistry because they ARE doing photosynthesis and need to do that in order to digest and extract chemistry for the entire plant to survive.
I do not like that they are watered from the bottom up. They need drainage, yes, constant moisture, but not a 'bog' situation for an indoor plant.
If I were you, I would chalk this up to winter and slow growth. When the light is low and temperatures are low, energy is maintained at low levels. More fertilizer during this time is a death sentence. At least an insect attack and or disease problem sentence. Leave your plant alone. Allow it this hibernation period. Keep the temperatures stable and do not over water.