leaves don't seem to be that strong

I don't think it looks that bad. might be over thinking it. Good Luck!

If you want to make your leafs and plant in general stronger you need to start applying silca like Rhino skin or something sim coming into wk 5. It'll help. Happy growing.

If your not using Cal Mag, then start. It helps more than pple think. Also your leaves are pretty dark green, with a bit of tip curl and that could be the start of nitrogen toxicity-dark green leaves that are droopy are nitro tox probs. If your not watering with plain water PH'd to 5.8-6.2 every now and then, then start doing so. Id run water with Cal mag in it one time and plain nutes the next and switch between them for a while and see if that helps. Its hard to judge based on a pic alone when we dont know your nutes, or have much of a diary to look back at and gleam info from. But aside from the leaves "not seeming that strong" as you put it, if there is no other issues that that, your doing well. Plant looks pretty good to me as well.

Your plant looks great. The droopy leaves probably just not getting the light like the top of plant.