This plant has always grown really well but recently the lower leaves have started turning yellow and falling off, and I now have an almost bald trunk on the lower part of the plant. Is this overwatering/underwatering? The soil is currently dry but I am scared to water it now in case I previously have been giving it too much. The rest of the plant looks quite perky. Will new leaves grow on this area when the growing season starts again if I pinch out the growing tip?
I am thinking that this is an issue with light rather than water. How much light is the lower part of the plant getting in that area? You should start rotating the plant every week or so so that all sides get some light.
There is a chance that it could also be underwatering or overwatering. If you overwatered in the past, I would check for root rot just to be sure that is not the issue (https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm).
Water the plant when the soil is dry to the touch. Even if you overwatered in the past, just water when the soil is dry to teh touch on top.