Couple more points --
- You still might need to provide supplemental light.
- Check for spider mites. They are my worst enemy in too early spring when I still can't put them outside, the house is dried out from the heat, etc. And when I'm starting to let down my guard thinking it's almost spring... They made it
If there are any webbing, that's a sure fire sign and bad infestation. If the leaves are losing color with microscopic nwhite spots on the surface, or turn the leaves over and look for tiny reddish specks.