Hi!
I see that you're watching the portions of what you eat, but maybe a suggestion is to watch what you eat. I'm not sure how your eating habits are, but portion size isn't always the solution. I'm sure you know, eating an apple is better than eating a cookie. Or another example, if you eat soup, try and stay away from the really creamy soups b/c those carry a ridiculous amount of calories. And just little unhealthy things here and there add up. If you're out at a restaurant and you order a salad maybe ask for dressing on the side so they don't smother it. (Dieters tip for salads: dip the tip of your fork into the dressing instead of pouring it all over your salad) ... I'm not sure if this helps you, but I thought i'd suggest it.
.. It's a lot about what you choose to eat too.
Also, since you don't like running, then don't run. It's much better for you to keep your heart rate up at the same rate for a longer period of time by continuous power walking than it is to run a short distance and stop. And plus it's easier on your knees. Eventually you're energy level will increase and then you can start jogging intervals during your walks. .. Distance and time is better than worrying about speed.
I hope this helps! :0)