Jules
Check out the carb content on the tin - I have found that a lot of canned stuff contains carbs. I do still have them though as there are a few that are low carb. Stick to lower carb veggies such as cauliflour - buy them in fresh at the start of the month and then freeze them in little blocks so you can just eat them when you fancy it.
You need to make sure that you check the content in a lot of things as there are hidden carbs everywhere.

Good luck x