No need to add more plants, it's just your spacing is very good for growth. I might top them out and put a 600 or 1000 HPS just for flower but I'm a little over kill and heat will be a problem you have to learn from.

You are absolutely right. Learn your room and get a few grows under your belt. That is what they had me do. Don't top or anything. Veg to about 12 to 16 inches and flower. The fewer the pieces to the puzzle, the easier to fix problems.

Keep us up with pic's.

Oh the other space could be veg room and mother room. Then you got a Sea Of Green. Now there's some work.