I by NO means am undermining your efforts. I'm positive you work out hard. However, our bodies are crazy machines that adapt super quickly so even if you are THINKING you are working hard, your body might not be burning as many calories as it was before because it's a lazy SOB. Fact of life.
Are you doing strength training? I can not stress enough how much weight lifting helps. Muscle burns 3 times more calories than fat, granted a pound of muscle only burns 6 calories a day, a pound of fat only burns 2.
As for the jogging/walking part, what I do suggest is interval training, like Mandalinn recommended. The best way to do interval training is to do high intensity, so roughly 90-100% effort (so you're seriously huffing and puffing and you can't talk) and then do a recovery (50-60% effort where you can talk, breathe, regain composure). Start off with shorter intervals, longer recoveries, then increase to longer high intensity intervals, shorter recovery. This will help increase your VO2 max as well.
A lot of times, it's not necessarily how LONG you spend doing something but how intense it is because you have to trick your body into thinking that it can't adapt. Unfortunately, it sucks because that means you always have to change things up, but it'll be fun because you can add things to your routine. I would add in body weight workouts (squats, push-ups, lunges, pull-ups, wall-sits, tricep push-ups) if you don't have gym membership. You don't need a gym to do strength training.
AND, sorry for the essay

Just trying to throw all possible ideas out there!