jo, does Milo have anything else during the day, eg in the way of treats, including training treats? It's just that the recommended serving size on the dog food pack is if that's all they have, so if Milo is having anything else, it might just be that he's not growing as fast now and not as hungry.
Alfie is 9 months old now and weighs 13kg; he has about 60g of kibble twice a day, plus a small handful (about 20g) at bedtime. I also keep a pocketful of kibble for when we are out on a walk and he is off-lead, and he gets a piece of kibble every time he "checks in" with me, plus something higher value whenever we do a recall or are doing some training. Plus he gets a knotted fish skin, a veal stick or an ostrich tendon each day, and maybe a few bits of kibble in his Kong Wobbler for a bit of fun. With this combination, his weight is stable and he looks just right - even though he's probably only having 150-160g of actual kibble.