I'm usually doing first LST on my plant around day 11 to 16.  So for the girl to look like that 15 days in?  Looks to me there's a problem.  I won't tell you what to do, but if mine was growing that slowly, I would abort.
But I grow autos.
I'm currently having a slowish grow because of a cotyledon that was completely damaged.  Gonna wait until I need to make new feed in 2 days to make a decision.  That being said, mine looks alot like yours (mine is more lime green, maybe a tiny bit smaller) at Day 5/6.
Hope that helped.