To be honest, with no nutes, she's not looking like bad or anything, just lacklustre. She's starting to smell though which is nice, obviously because so small nothing major and no carbon filter needed yet, but its nice.
They are growing slow as you say...i would suggest you to rise a bit the temp expecialy during night time ( roughly 19°C)...and double check if they are in an under/over watering situation...are you giving them some nutrient feed?
@jackjack, Ok i'll see what I can do with the temperature at night.
I don't believe I'm watering badly but watering and nutrients seem to be an issue for me that I can never get right, so I'm abstaining from nutrients at the moment.