i say get a 90watt LED ufo in that space or better yet like 180watt led panel, i recently ordered one (ufo) and they are great. you get alot thicker buds and alot less internode spacing. your plants look really stretched no offence.
the 90watt leds a bit spendy $200, but they replace a 400-600 watt hid lamp and they will pay for themselves though in the electric bill compared to the other lamps. You get decent yeilds, way better than your getting now.

your are looking decent for what your using, keep up the good work on that point