I'm working on losing some weight too, and I think the skin thing might improve for you gradually, but there will always probably be some "looser" skin on your tummy. There is no cream that will fix that. (DON'T fall for the ad's that say so.) A tummy tuck would, but that's pretty drastic. My own tummy is stretched to bits from pregnancy. I have more stretch marks than normal skin, I think, and no matter how thin I may someday be, that won't change.
Some of the sagginess, as the PP mentioned, can be helped by toning up those muscles. I think running helps a bit for that, but the really great ones for core body strength, to the best of my knowledge, are exercise ball routines, and pilates. (perhaps someone with expertise here can add/correct me.)
Your diet sounds pretty healthy - make sure you keep up some low-fat protein intake, and drink plenty of water.

All the best!