Have you gotten your body fat percent measured?
I had my goal weight set at 160, but when I went for a DXA scan I found out I have 140 lbs of lean mass, which means 160 is just too low - I would have only 8% body fat, which is okay for men but not for women.
If your lean mass is "too high" you would have to lose lean mass to lose weight (which is possibly problematic), but alternately if your lean mass is too low, you might have trouble losing more weight because your body just isn't using more calories than that (and I was reading somewhere on here that once we've been obese our lean mass is more efficient at using the calories, too).
Anyway, it might be good to find out what your body composition is, so you can have a better idea of what might be going on. There are lots of ways to get it tested: DXA is now considered the best, but it's expensive. They can do the fat-pinching test at the gym, which I think is pretty good... I don't think the electronic scales that measure it are very good because the results change depending on how hydrated you are, but I'm not an expert. Maybe look into it and see what might work for you.
Just an idea.
If you're low on your lean mass, I think the best route is to start using weights, or doing weight-bearing stuff to get your muscles building up, like squats. It sounds like working big muscle groups has the most impact.
If you're high on your lean mass (a lot of us probably are, because we were carrying so much weight around for so long!), I think it's probably good to look at your goals again, keeping in mind you're healthier than you thought you were. Then maybe work with lighter weights and more repetitions to be more toned and "sculpt" problem areas.
My DXA scan guy (he also works in the cardiac clinic I go to) said it's fine for me to lose some lean mass along with fat (which is what happens when you lose quickly - a lot of it is lean mass that you're losing, not fat), so I might end up lowering my goal weight depending on how my lean mass decreases. But since I plan to lose about 3 lbs per month, I'm unlikely to lose very much lean mass. Just thought I'd tag that on here in case it's relevant to you.