you are definately over watering and perhaps over fertilizing. youd be better off watering it once a week, maybe less. and washingtonias dont need much fertilizer maybe twice a year.
as for the bannana, you can expect it to grow about 3-6 feet in one year.

Washingtonia are pretty much desert palms, so watering it once per week is plenty! Maybe once per week is too much. You can see them growing like weeds in Las Vegas in dry cracks along the sidewalks and roads, and they hardly get ANY moisture, ever. When in doubt, purchase an inexpensive soil moisture meter and only water it when it's getting close to being dry. Never water it if the moisture meter still says "wet". Good luck!

Unlike the Washingtonia, musa and ensete can take a fair amount of fertilizer. Best to give them a diet of fertilizer on a regular basis like every month. They tend to do very well if you give them an organic fertilizer like Milorganite. You really can't burn them by giving them too much Milorganite.