my knowledge is limited in this stage,
but maybe? Don't you water a bit too often? Aren't you using too much nutrients? I completely didn't use my nuts untill the second set of true leaves were formed, I think Zandor told Rastagal this was the best way, since overferting in this stage can indeed burn out your plants quite quickly.
Just maybe, vent the growroom even more, has a tendency to straighten out droopy leaves.
However i do not know for sure. Let the Brains clear it all up

ah look at me, info-bumping like a lil' bitch Someone help this kid!