Sorry to hear that you broke your wrist so badly, but fortunately it sounds like the cast is off and you are healing up! It does take quite a while for the area around the broken bones to feel completely back to normal. In large part this is because when you are in the cast your muscles under the cast are immobilized. When muscles are immobilized, they begin to lose mass and become weak. Their tendons also start to stiffen up. When the cast comes off, it is very common to have significant weakness and stiffness.
Fortunately, the solution to this is simply to keep slowly working with the wrist and trying to use it. The muscles and tendons will return to normal over a period of several weeks. If the pain is significant, you could try some over the counter pain medicines or your could talk to your doctor
to get their advice.
If you find that the stiffness and pain are not improving with slow and gradual exercise of the area, you should go see your doctor. It is possible that you need a more intensive physical therapy regimen, something that they will be able to prescribe.