I agree on this. Although I have 2 dogs one is 6 lbs the other 8. They eat to meals a day. I put their food out in the AM - and they do eat well in the morning, I leave out and assist sometimes for about 15-20 minutes and them I pull it up. PM - I leave down for about an 30-30 - 45 minutes.Normally I would suggest the 15 minute down pick up rule and some tough love for picky dogs but since your dog is young and a small breed it is important he eats. How is his weight does he excercise much?
He could be just eating all that he needs. I would keep the treats down to a minimal for training only and skip all table scraps. I would continue with the 3 meals a day until he hits close to adult weight. Once he gets older, I would go the tough love route.
I asked the vet about this, he told me their weight was great and they were healthy and he seen no reason to feed three times unless they needed it.