Slow Growth

So I've got a small issue. I'm currently growing 2 feminized northern lights seeds and the process seems to be going a lot slower than I previously expected.

I germinated the seeds nov 1. Started the seeds off in some small cups, then transplanted straight into some 3 gallon containers using just some normal potting soil and watering with plain distilled water. I think I may have stunted growth when I transplanted them, since growth was very slow for the first couple weeks.

I switched from cfls to a 400w MH lamp a couple weeks ago, and growth moved faster, but they are still only like 6 or 7 inches tall. I have the lights on 18/off 6 hours a day (the grow area is a closet in my room, and the hum from the ballast is kind of loud). Will the plants grow faster if I use 24 hours of light. Any other suggestions for speeding up the process?

What are your temps? Do you pH your water?

I'm no pro at all but I know I read before that if you transplant into something that's too big it takes a while longer for the plant to react cuz the root growth needs to happen before top growth can occur.... maybe someone can give you a little more info on that

It sounds like you might not have enough fresh air for your plants

I have plenty of fresh air. The closet is 4 feet by three feet. and about 9 feet tall. I have one oscillating fan and a 4 inch vent (cut a hole in my apartment wall, haha!) using a bathroom fan running 24/7. The temps go up to about 85 with the door closed, so I just keep it open for now. They stay around 75. I figure I will cut another hole in the wall when I plan to flower so I can keep it closed and control the smell. The ph is 6.9 at the moment.

The plants seem to be picking up their growth in the past few days, and they both seem pretty healthy.

alot of times they just slow down and then all of a sudden you get a BIG growth spurt...i wouldn't worry too much...seems like your getting it under control