I carb count also. Khaleb can have a morning tea of less than 20 gm carb without insulin, an afternoon tea of less than 10gm carb without insulin and a supper of around 15gm carb to get him through the night without insulin. Are you on a pump or injections? If Khaleb were particularly hungry I'd still just feed him even if it meant I added that insulin to next meal. If he was hungry late in the afternoon I might give him his meal early with insulin and another snack later. I, like Leggott, wouldn't want to give Novorapid injections too close together.
It does all seem confusing at times. Once you get used to the speed that insulin works it does become easier to judge whether your child is going up or down at whatever time of day. I truly believe my brain has a devoted little spot for diabetes now.
It is all trial and error but don't dwell on the error and keep a record of the trials that work.
All the best. Carb counting does make life easier and I have found this especially so when it comes to other people looking after your child.