4 week plants, stem seemed to stop growing. HELP!!

hello all,
I'm a first time grower and im growing 5 plants, 1 White Widow and 4 Reg plants, that are 4 weeks old. They look healthy, beautiful green leaves, but it seems that at the 4 week stage they should be a lot fuller. 2nd of all, my stems dont seem to be growing at all and the leaves are growing excessivly slow. I give them 16 hours of light and 8 hours of darkness. I use Scotts Premium Potting Soil in 7" x 10 1/2" pots, water is draining, but the soil is staying moist for days. So my watering schedule is like every 5 days or so. That doesnt seem right though. Please tell me what Im doing wrong. Im doing my best here. I've posted pics of the regs and the 1 white widow. Thanks for the help!!

if that soil has premixed nutes its probably freaking those sensitive baby roots out. for 4 weeks those are tiny, just wait it out.

how far is your light away from the plants, at 4 weeks they should have 4-6 nodes. the soil looks like it is dense, if that is the case get some perlite and mix 50/50 with the soil and replant i would guess that there isn't much root down there

The lights are about 3 inchs away from the plants. there is already some perilite pre-mixed into the soil. Should I put more in?

My week old seedlings are exactly that size. More light. And be patient. They're probably putting on mad root growth. The tops will catch up.

@dannyboy602 thanks for the advice! Just over night my plants are looking better with more light!!