Hi Samantha6,
hm, from a general space Feng Shui perspective I think you can also place water in the Southeast and East.
A good idea is to balance all elements in the room to create harmony (Earth, Fire, Water, Wood & Metal). If there's an imbalance (not enough light) it might be a good idea to place another lamp.
Depending on what additional information you have, there's a lot you can do. If you have level 3 of the course, then you could check the period of your office & waiting room and place appropriate cures or activations ...
Best wishes,
Astrid