You're demanding? He lacks inner discipline?
Inner discipline comes from security, which comes from being loved. No child has inner discipline. We as adults should have developed it, and we instill it in our children through the security of knowing they're loved, through clear boundaries and logical consequences, and through consistent routines and the safety of home.
A little child who didn't even exist on this planet more than 5 years ago is in the state's custody, has a demanding caregiver, has obviously had more than a couple of parental or guardian or caregiver situations, has probably experienced neglect or even violence, and is now been in a new home and school for less than a few months will not have inner discipline. He will have fear. Trepidation. Insecurity. Worry. Doubt.
Wetting his pants is not a sign of inner discipline. The problem is that he's unsure of life, of where he belongs, of what will happen if he is "not good enough".
Love him. Hug him. Soothe him. Provide him with safety.
As for the demands, be demanding. But of yourself, not him. Demand of yourself consistent and logical routines for him. Demand that you create an environment where a small child feels loved and safe. Demand of yourself the ability to create a confident boy who will grow up to be a confident young man who knew that he was loved, that there were rules (logical, applied with kindness and consistency, and boundaries, and logical and reasonable consequences for not obeying them), that he belonged somewhere.
In that way, you will create the inner discipline that you desire for him.