Looking at your stats 3.5lbs loss is fab and if you looking for a quicker fix maybe slimming world isn't for you and you are expected to loose 1-2lbs a week. It's a healthier eating plan for life and losses can be slower than on other diets- but exercise will help boost them. But unlike other diets you are never hungry. BUT in saying that your loss is fantastic!
A speed food is a food lower in calories for the group it is in like fish and chicken are speed foods for meats as they are lower in calories per 100g then other foods that are meats. Superfree are most fruits and veg and on extra easy you need to fill all meals with a 1/3 of your plate and choose them first for snacks. However starchy veg like potatoes and sweetcorn and peas don't count towards your 1/3 superfree as they NOT superfree.
Hope that helpsx