I agree with others who think your soil is too hot.
With autos you only get one chance to get them through their short veg stage.
If they get too many nutes at this stage they can stunt.
Autos dont need as many nutes as reg plants and your pro mix soil has prolly
been made up for regulars.
You could maybe try to flush some of those nutes outa there,and see how she gets on.
But i dont think your poor ole plant will produce much now.
Its way behind its time schedule,it should be about a foot tall by now.
What is the NPK of your soil by the way?
GL