what made the difference for me, in terms of weight loss, was running over 20kms three times a week. (I don't seem to do that any more however).

Up until that point, I didn't lose much weight, but after I started doing that it just fell off.

So far it has stayed off no matter how much I run, or don't run.

Try some longer runs at a really slow pace (it's ok to walk for a bit too) and see if that makes a difference to your weight loss.

Failing that, just keep doing what you're doing. all exercise is good for you no matter what weight you are ;-)