Why she is growing so slowly, she gets all the sam...

You could also strip some lower growth making her stretch some looks not too bad though maybe a bit too much n she may have weaker tolerance to nutes than the others

The leaves are a little dark and have deep ridges, this could mean overwatering. Also maybe don't let the room get so cold in the night hours vegetative plants like a warmer humid atmosphere. Overall the plant is looking good don't make to drastic of changes, your close maybe add a day between waterings.