2/3 days without any noticeable changes in hight o...

Hi @Jonobo! Your medium looks really wet. Roots need to be on a wet/dry cycle to properly expand, searching for water. However it should never be 100% dry nor 100% wet for too long, and in your situation I think you're under-watering. Give it a good liter of water but not straight at the plant's feet: circle around the outer border of your container, it will encourage roots to spread and your plant should grow vigorously again. Another hypothesis could be your compost being too strong, such a young autoflowering plant doesn't need huge amount of nutrients, on the opposite this could stunt her for a while. Hope this will help, keep us updated and happy growing! 👊