Not all weed plants will grow to be the same height! I grew one that only reached 21" and another one that got to be over 50".. always check out what the seedbank indicates is the approximate height for the strain - and understand that this, along with their harvest estimation, is exactly that - an estimation! The strain I grew that went over 50" was only supposed to get to 30"... So you just go with what you've got! And you've got a nice looking plant that is perhaps in need of a bit of defoliation at this point.... get some light to the lower bud sites and increase the airflow to the interior.
Good luck!