Broken humerus on left arm

Hi i`m a 29 year old man i fell on black ice a week ago, this left me with a humerus fracture on left arm, but at a and e they managed to give it better shape and now it is just broken. I have no pain in my wrist hand or shoulder, but above my elbow it is stiff and sore. I had a cast which was changed and a different sling put on yesterday, the bones need to fuse together and are in a decent position, when i leave the arm in sling it seems quite low not sure if this is arm maybe getting a bit straighter when i was sleeping, my dr said i shouldn`t be letting it hang like i had to in first week, so when im on chair bed etc should i move it so it is along my stomach or let it go to my side? Thanks for any help and advice