ok with the dimensions you provided you have a total of 26.5 square feet(floor space) for your grow area. but since your only doing 6 plants at a time you should be ok.

why such a big space if your not using it all? ideally you want 50watts+ per sqaure foot during flower and 30-40watts for veg. you might want to block off some of the extra space when you flower to maximize light on plants.

does the room have mylar or white walls to reflect light?

good luck growing cant wait to see some pics