Sydnerella's Mama is exactly right... you won't lose weight no matter how much you exercise if you don't feed your body enough. It sounds ridiculous, yes, but think of it like a fire. You have to keep feeding a fire to keep it burning. Exercise is like a couple of puffs of oxygen on a fire - it burns faster and brighter, so your body is burning off extra fat when you exercise. However, it will go out completely if you don't feed it!
If I haven't hit my points target for the day, I have some fruit, or a 2 pt snack - those 100 calorie snacks are AWESOME for this! I like the protein bars. They really fill you up, and since it's "extra", it's like a treat.
AND, please remember, you're human. Falling off the wagon is only bad if you don't get back onto it again, and you are! Let it go, and focus on the future, not the past!