You look absolutely fantastic!
You should be so pleased loosing such a massive amount of weight.
For your stomach, do you do any toning exercises? Just a few reps of sit-ups, or the plank every other day can make a big difference, and also a lot of the kettlebell moves work the core so they're great for toning the stomach. They cost about £15-£20 from places like Tesco and there's loads of videos on Youtube that show you how to use them x