If you're unhappy with how you look, one thing that can make a HUGE difference is weight training. Not sit ups, they don't do that much, but try something like this:
http://www.womenshealthmag.com/fitne...ly-fat-workout or
http://www.cosmopolitan.com/advice/h...runches#slide2.
Adding those in maybe 3 or 4 times a week should really help. I added some really light weight training for my arms and it did wonders. You're already doing the cardio which is awesome. If you want you could try increasing how far you run by a mile or so.
Last but most important, I've found that weightloss is 70% what I eat, 30% how much I exercise. It may be different for other people, but that's how I work. Try keeping a food journal for a week or so and see how many calories you eat in a day. 1600 is a good number for you - I'm an inch shorter and that's what I shoot for. My problem is snacking. If you don't keep a food journal you could be getting extra calories and you just don't notice. WHAT you eat is really important too. Try increasing your green veggies!

When my family orders pizza, I try to eat a bunch of carrots/broccoli/celery before I eat the pizza, to help myself fill up. That way I can enjoy a slice but by the time I eat it, I'm on my way to being full. And as always, drinking lots of water helps. When I drink soda or eat stuff with lots of sodium, I bloat. It's crazy how visible it is (to me, at least). Drinking plenty of water helps keep you from bloating. Good luck! I can't wait to be 170 - I've been fighting to get out of the 180s for months.