When I make meatballs, with 1lb beef, ½lb Italian sausage and ½lb veal, I don't use bread crumbs, I use shredded bread. My mother used a box grater to shread day old bread, I use the food processor.
I cook the meatballs by simmering them in tomato sauce for 45 minutes. As they simmer, the shredded bread absobs some of the sauce and they actually increase in size.
If you use ground Italian sausage instead of ground pork, you do not need to season the meatballs!