Looks like your girls need more light. Given the 2'x2' size of your grow tent, a good starter would be a Bloom Plus 1000 or their 1500 model. You'll need to keep a close eye on heat gain since your ceiling height is so low, but these have the capability to be dimmed it need be. I use quite a few of these in different configurations as well as a couple other manufacturers, and these are are to heat at $80 for the 1000 and $120 for the 1500.
Good Luck and happy growing!
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