Despite it's name this plant isn't a palm, and isn't even related to palms. But it is a dry climate plant. Its swollen base is for storing water to help it through prolonged dry conditions. The sunny part of how you're keeping it is good, but the higher humidity of a bathroom and too much watering isn't good for it. Try to get it into a drier environment and in winter you shouldn't need to water it more than monthly.

Put a saucer under it. That will help.