Looking for some advice for my Dieffenbachia. I've had it a few years and it just never seems to be happy. It slight droops all of the time. I've tried different watering schedules and different lighting situations. It hasn't been repotted in over a year. It's currently in a 12 inch pot and the plant is around 50 inches tall. The vent by the pot is closed. Pic of the soil mixture in case that is the issue. Thanks!

