90% of weight loss starts in the kitchen, so that's why you're getting some results by reducing your sugar intake. You would be surprised what has sugar in it, so learn what to look for in food labels. Anything that includes an ingredient that ends in "...ose" is a sugar. Dextrose, fructose, glucose, lactose etc.
Since you seem to enjoy walking why don't you include some intervals in there with sprints. So walk, sprint, walk, sprint. This would help you. I'm a big fan of lifting, that will also go a long way.