Small for 4 weeks?

So this Is my first grow and it's been 4 weeks since she popped out. I didn't have good lighting at first but upgraded and got some good CFL's on her and she instantly grew like crazy but recently it seems like she's slowed down and I'm worried she's way to small for 4 weeks. Can I get some input on this as well as when I should switch to 12/12 I currently do 24 hrs thanks!

she looks a little small for 4 weeks, but healthy. i would give more ventilation maybe to strengthen the stem and maybe get the cfls closer. and i'd wait at least a couple weeks before switching to 12/12 if you want a decent harvest. peace