We cannot advice on insulin doses.
If you are carb counting, you should know what is your insulin to carb ratio.
For example, there are 85g of carbs in 100g of Rice Krispies; if your ratio is 1 unit of insulin for every 10g of carbs eaten and you eat 100g of rice krispies, you would need to take 8.5g of insulin.
It is unusual to have an insulin to spoon ratio as different foods weigh different amounts.
If you want some revision on carb counting, you may benefit from the
Bertie Online course.