Half a pound a week
is progress, IMO.
My experience with my body is that simply adding weight training does NOT guarantee weight loss. Diet has been extremely important for me, as much as I wish wish wish it weren't so. Almost-daily cardio is super-important as well. I'd say look at your food intake, both quantity and quality, and consider revamping your cardio to make it more effective. You may just need to fine tune things a bit to get more results.