Hello Cadur, vague questions do not exist only vague answers 😜
This is a beautiful plant and the reason for her staying so small is because of the genetics.
Look at this information that I've got from the RQS website:
Royal Jack Automatic will not grow too tall, reaching a height of 40–90cm, which makes it ideal for smaller or more discreet grows.
I also have to mention that you did a beautiful job with the LST training technique!
Goodluck and enjoy your grow!