He doesnt eat much

Rocky is 13 weeks old and coming on really well. I'm just not happy with his lack of appetite as I thought all pups would eat for England but Rocky doesnt.
The breeder told me Rocky ate Scrambled eggs/Beef Mince/Sardines/Roast Dinners [lol] and dog biscuits which he supplied a bag of but he doesnt seem too keen on anything [other than the Roast Dinner]- all have been tried and tested.
I now give him some James Wellbeloved Biscuits for breakfast but he doesnt eat them.
I then give him cooked mince and the James Wellbeloved Biscuits mixed in at dinner time.
I then give him cooked mince and the James Wellbeloved Biscuits mixed in early eve.
He needs encouragement to eat his two meals but wont always eat everything in his bowl. He's just very laid back about eating full stop. He isnt thin and he weighs 7.5kg.

Should I try something else or stick to what I am doing?

I'd stick to what your doing bob, he's healthy and happy. Darcy is terribly fussy and always has been, I've spent the last year worrying about her eating, but she's healthy and happy and weighs 16.2kgs so I'm a little more laid back now

Stick to what you're doing, but maybe decrease the portion just a little for the last meal. That way he should be hungry in the morning for his breakfast!