Tracey,
The simple answer is to test!
Always, and more-so whilst getting use to insulin/carb ratio's regime, is to test on the 1, 2 and 4 hour mark after eating, this way you will know that your ratio is correct. It is really all about eating and testing to establish the correct amount of insulin for each 10g of carbs.
Without causing to much confusion, you will find that your insulin requirements will differ at different meal-times throughout the day, this is why you need to enroll on the DAFNE course as soon as possible.
Nigel