I'm browsing pinterest for ideas. Here are some suggestions:
http://www.myrecipes.com/recipe/mexican-tortilla-soup-10000001571541/
I change the recipe slightly when I make it. Adding things like chickpeas, beans, zucchini, and squash (not all at once) to make it more filling. You don't need to have the chips or cheese on there.
I love pureeing the entire soup (except the chicken) so it's smooth and creamy. Before I eat a bowl, I'll cut up chunks of avocado and put that in. Absolutely delicious.
Plus, if you omit the chicken, cheese, and chips, it freezes well.
I can't recommend some of these other soups, but basically stick with lots of veggies and some broth. Meat if you want it.
http://www.skinnytaste.com/2011/12/crock-pot-chicken-enchilada-soup.html
This one might be too carb heavy (nearly 30g) but you can omit some of the ingredients to help with that. I think it's from the black beans.
http://skinnyms.com/slow-cooker-chicken-chili/
9g of carbs!
http://skinnyms.com/fiesta-chicken-soup/
13g of carbs
http://pinterest.com/search/boards/?q=slow+cooker+soup