Yes, you are right, @RiiSi is an expert and we've admire the pictures of her boys!
Your boy seems to be the same size as Castor - who is 3.5 yrs so fully grown. His parents were quite lean (he looks very much like his father, in fact), but they were one size bigger (about 25 kilos). Vets here think Castor looks fine and he seems healthy and happy... but hungry. We're upping portions little by little so will see if that has any effect. I'm nto really worried about his size (after all, at 3.5 he probably won't be any bigger) but I was rather wondering how to up his portions!
A "typical" hungry? That's normalā¦do you add snacks in throughout the day? That helps quell - frozen green beans? yogurt?