Darryl’s Analysis

Environment:
This area is very poorly lit.  The best any “bright indirect light” plant will do is right up close to the window: maximizing the view of the sky is the first priority to get good “bright indirect light”.  The second priority is to make sure the duration of DIRECT SUN doesn’t exceed 2 or 3 hours.  With such poor light, the plant will only disappoint after several months of losing almost all of its lower leaves no matter how you water the plant.

Effort:
Your watering strategy will work when the light situation is improved.

If you want your plant to grow well in the long run, you must use fertilizer – more info on fertilizers here.

Expectations:
The two factors that have the biggest impact on how well your plant grows is light and your expectations.  I find these Dieffenbachias with the lighter centers (like D. ‘camille’, ‘honeydew’, ‘star bright’) don’t hold on to their lower leaves very well when grown in home conditions.  The only one that stays nice and bushy is the ‘Tropic Snow’.  Regardless, you should expect lower leaves to fall off – which happens even in a tropical plant conservatory:

Look at the trunk of this Dieffenbachia: many leaves have come and gone.

If you want to learn a healthy, balanced approach to houseplant care, check out my online course or my book.