How long have you been doing this? It can take up to 6-8 weeks for a new lifestyle change to show up on the scale, especially when you're adding exercise. In fact, if you start exercising to lose weight, it's very common to see a slight upward shift in your weight as your body adapts to the new demands you've placed on it! It's normal, it's temporary, and it's NOT FAT.
Here's an article that will explain what's going on with that: www.sparkpeople.com/community/ask_the_expe
Now that we've got that out of the way, let's talk about nutrition. Frankly, watching what you eat isn't enough. :) That means different things to different people, but most of the time, it means you're doing stuff like avoiding junk, eating more vegetables, etc. That's AWESOME, and a great first step. However... it's not enough! In order to lose weight, you have to eat less than you burn through daily living added to exercise. If you don't get your nutrition under control, you won't get ahead of it. You can't out-exercise a bad diet!
Are you tracking your food? I mean really tracking, not just guessing and entering it into your tracker. Most people really, really suck at eyeballing. Only 11% of Americans actually know, accurately, how much they eat. Break out the measuring cups and scale (if you don't have a food scale, get one, they're invaluable, and inexpensive) and KNOW what you're eating. Track every morsel, every drop. CAlories add up FAST, faster than you realize!