My lo is 7.5months and weighs just short of 9kg. Im no expert but its good to know what other people do.
Could it be a GS? (not sure if they get one around this age???)
I have dropped the df as of 3 weeks ago and he wakes up hungry so he has a big b/fast of 5oz (150mls) of milk and cereal (ready brek or a whole wheat biscuit)
This is our routine, its very similar to yours:
7am milk and cereal
10ish 6oz milk (180mls)
12noon lunch-today half piece bread with quarter of banana spread on (finger food so not sure how much he actually eats) and yoghurt (ate it all)
2.30ish 6oz milk
5ish dinner-toady will be butternut squash soup, usally no dessert as he has a good size portion but today we have strawberries and cream so he will no doubt feed himself a strawberry or 2!
7ish 8oz milk (240mls) (may only have 6oz)
HTH
When your lo is hungry after his 1st meal have you tried giving him an extra milk feed instead of extra solids?
I think you should aim for a minimum of 20oz per 24hrs (someone correct me if im wrong), my lo takes around 22-25per day so towards the low side, but i do add milk to a lot of his food eg in soup, with pasta sauces, or even if his meal looks a bit dry i add abit, or if it needs cooling quickly theres usually a feed made up in the fridge so i just put a bit in, you could try doing that if you want to increase his milk intake.
Babies don't over eat do they? So if your lo is eating an extra meal he obviously needs it so i would feed him, but i would try offering him extra milk first tho.
As i said im not an expert but i hope that helps x