I am definitely no expert - quite the opposite, Iām a complete beginner! But Iām 7 weeks into my first grow and in week 4 and 5 my plants were still fairly small and my expectations were pretty low. Then all of a sudden within a week or so they easily doubled in size. I was having to adjust the lights daily by about 10cm ish. I canāt offer advice but I had the same worries as you and now the plants are so much bigger than I ever expected. Good luck with them :)