Hi Elaine and welcome to the forum
What were the breeders feeding your lab before he came to you. I would be getting him on to a good quality complete puppy food at that age. (Do so gradually or he will get a bad tummy). If I was given chicken fillets and plain boiled rice I would probably pick out the chicken and leave the rice too!! Then put his food down at mealtimes and pick it up again after 20 minutes if it is not eaten.
Perhaps you need to up the enthusiasm when you call him to you. He needs you to be really exciting to come to and loads of fuss when he does (even if it involves sounding a little silly with lots of yays what a good lad when he comes) Call him with a high pitched exciting voice. As you have small children puppies get used to their name being called out by the kids ad lib and learn to ignore it. I get round this with dogs that are around children by using a 'recall name' saved for when I wish the dog to come to me. eg his name is Tonks so he is probably hearing Tonks quite a lot irregardless of whether he is called to you. Therefore a nice long Tong-ky could be his recall name.
The same principle with Toys. Save some toys, the ones that he is more interested in for playing with you and don't leave them lying around. Be animated and excited enticing him to chase them in your hand and keep the games short. If he sometimes likes a ball try rolling it initially and not too far. Again you finish the game before he loses interest and don't leave the ball lying around for him to entertain himself with.
Lastly he will need plenty of sleep and tire very quickly at his age. Good luck!
