Bro, I think I know what your problem is. I have been dealing with this same issue myself for the past week since I am a novice grower. If you leaves are droopy, then it is probably overwatering that is stunting their growth. But the problem I had is that my soil didn't have enough nitrogen in it. This is common with walmart or lowes brand soils or even miracle grow organic. Do your leaves look yellowy-green? Probably nitrogen deficiency. Young mj plants need a lot of nitrogen to kickstart their growth. I would say get a fertilizer that is high in nitrogen for them and use it next time you water. Let your pots dry up pretty well and then add the ferts. Fox farm is going to be the best, but if you cant get that, just use some miracle grow bloom fertilizer. The miracle grow should be fine if you start off with maybe a half dose and gradually increase to a full. Cheers and good luck!