How big is your bowl of oatmeal? Do you have more protein with it than just a bit of peanut butter? Do you eat any fruit with it?
Rather than turning to crackers which are really fairly empty calories, as in not filling, why not try a piece of banana and some yoghurt, or a couple dried fruit like dates or figs? I never eat a whole apple now - I cut it into 1/3 or 1/4, and then slice that up and nibble on that. If I am out, I just put it into a little snap-lock bag and squeeze the air out. Pears are good for this, too!
Below is a link that you may find helpful: www.sparkpeople.com/resource/nutrition_art
If you are using your Nutrition Tracker, then keep a diary of what you eat and when, and then also write down what was happening. You might be able to find a pattern and then deal with it more successfully.