Well, to make this a bit thicker (which usually tricks me into thinking it's more filling) you could make a roux. All you need is a couple tbs of flour in between sweating the veggies and pouring in the broth. Mix in and brown up the flour a bit, this helps give a nutty flavor the more you brown but thickens less the more you brown. If you're not on a diet this then makes a pretty good pot pie filling, too (or just put in a ceramic oven safe bowl and put a square of puff pastry on top at 400 F, perhaps a bit of egg wash for color). If it's too soupy you can also experiment with adding noodles or rice to suck up excess moisture and give the whole thing a bit more structure. I'd also probably add celery in the sweat (because France) and mushrooms (both because I love mushrooms and the earthy/savory flavor helps it not be so leafy/veggie/unsatisfying).