So you don't eat much but are not losing weight?
The best advice i can give you... keep a food diary. Write down what you eat, when you eat it, and weigh yourself once a week. Forget about losing or gaining weight, its just an exercise to track patterns in your diet and metabolism. In a couple of weeks or a month, if you are still worried, you will have something to show your GP.
If you don't trust your GP to help you, find a new one.
BTW Cleigh, your little one was sick recently, how did you go with that? I posted on your thread but you didn't check back with us