I am in 9 square feet, same as you.

ive been doing tests,
1st grow 8,000 lumen 1 plant 4 bulbs 150w/75w/24w
2nd grow 15,000 lumen 6 plants 8 bulbs all 24w
3rd grow 25,000 lumen 15 plants 14 bulbs all 24w


satisfied each time! that's a fact