Are you using the Sparkpeople nutrition tracker, or a plan given to you by a dietitian? I'm unclear on that point from your post.
You can set your Sparkpeople Nutrition Tracker to give you suggestions for a meal plan for pre-diabetes. You don't have to eat everything that plan says, but it might give you some ideas for the types of foods that will be best for you, in the portions that you need. And if you track what you do eat, you can run the reports to make sure you're getting the protein and fat amounts you have been prescribed by your dietitian.
It's an adjustment, good luck!
My Sparkpage is set to private, but I'm open to SparkMail!
"People often say that motivation doesn't last. Well, neither does bathing--that's why we recommend it daily." - Zig Ziglar