Stupid question but are they autos? If they are, autos are different to photos and growth occurs quicker, the vegging state has to be rapid and it has growth spurts. It's good that you are seeing pistils, I might be mistaken but I think I see shiny crystals on my 2 week old plant, can see it glitter in the sunshine!
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The northern lights cross will remain small just keep it in mind when you question growth, look at the different cycles of growth, I.e when do pistils form etc. Sorry for hogging your post lol