what are your temps like? can you control them?? if so id grab some bigger bulbs like 68w or a bunch of 42 or 55 or whatever you can get and fit as many as you can in both sides i know it sounds weird but id add as many lights as i could until i almost couldnt keep it cool enough LMAO
but yes adding some lower on the flower side would help the bottom buds im nto sure on your method of grow but your going to want a tall plant to be 2 inches from the lights at all times for dense bud being set way up like that with cfl's in my opinion from what ive read produce stretch and cause fluffy bud we dont want that id start by adding two 68w 2700k bulbs can get them from lowes not sure if they have those around you but yeah..... if temps hold out start replacing the others with the bigger bulbs until it starts to get tough to keep temps then thats your threshold of most light for the cab unless adding better ventilation.
is that a homemade carbon filter?
whats your grow style?
tell us more and take pics i love getting ideas from others i like the light trap thing you got there in the middle
again looking good need updates