Yeah I'm doing a Northern Lights from feminized seeds as well and mine is only 6 days from first sprouting and is bigger than that. I don't bother with any high end soils, I go with a mixture of my own compost and Miracle Grow potting mix, all sterilized in the oven, then limited veg and flowering nutrients. I've never had a problem with slow growth. Now I'm no expert, just a guy who loves plants of all kinds, but I have always had my best success with as simple of a set up as I can manage (except lights). Hope those girls start pushing soon. Good luck!!!