is he having regular bowel movements??
maybe cause he doesnt eat that much when it comes to dinner time his stomach is still carrying round food from lunch n any other snacks n also from his bottles.. which can cause him to over eat n his stomach wouldnt be that big to hold all the meals n resulting in him vomiting iykwim???
also if his movements arent regular he could also be constipated which can result in vomiting..
maybe cut the yoghurt out for a night n see how he holds up after eating ???
GL xox