Try to exercising more often. And maybe you need to increase the intensity. Are you breathing heavy and working up a sweat?
8 glasses of water at a minimum.
You don't really need to diet if you'd just eliminate the whites from your diet - white flour, white sugar, white rice, white creams, etc. My friend was diagnosed as pre-diabetic and so she did this and lost 20 pounds in just a couple of months.
Protein is a big factor, so make sure you eat a protein at every meal. And of course, lots of fruits and veggies.
Soda is really bad for you, so you need to eliminate it. Try sparkling waters instead. Or limit yourself to one diet coke a week. And I'm a chips & salsa addict, so I know where you're coming from. Try to limit this treat to once a week and make sure to buy baked or multi-grain tortilla chips, or Sun Chips.
Good Luck, you CAN do it!