People are divided over what you should spend your points on. Some people say you should stick to low calorie, low sugar, low fat (etc etc) snacks/foods, where as other people say as long as you use all your points, it doesn't matter what you use them on.
I think if you consistently lose weight doing what you are doing, then don't change it. If you're struggling one week, perhaps cut down the treats and up the veg and protein, and see if it makes a difference.
Personally I tend to base my points on low cal treats such as fruit and bulk out my veg and protein. I allow myself one "treat" a day from WW - so I usually have a WW Toffee Bar. But during the day I 'll have a snack such as Snack a Jack or Pink and White for 0.5pts each.
I hope that helps!