I remember when I was doing slimming world the lady used to say about hitting a plateau with your weight loss, where your body just becomes used to what you are doing, and you need to find something else to kick start your weight loss. Have you become a bit complacent with portion control, do you need to cut down on the number of sins you are allowed, more exercise? Do you do slimming world with a group, maybe the leader can give you some ideas.
Hope something kicks in soon for you, it it demoralising when you know you are being good, and nothing is happening isn't it?