I think my plants a dwarf

I started my first run with bag seeds and have only one plant , this is like a practice run for me to see how my system works out . The plants a month old and only 4" tall but real bushy I had it on 24/7 cycle for 3 weeks and switched to 18/6 , not alot of growth in the last week.
My grow room I built in the back of my walkin closet. 2' x 3.5' x 4.5' I'm running a 400w mh for this grow. I'm using flow nova grow and B.seaweed additive . Is this normal growth or is something wrong I'll post pic soon

post a pic....maybe just got a real bushy one....even happens even when you buys expensive seeds

Have to go get new comp cord for my camera , will be posting pic this afternoon